refactor(api)!: one namespace per feature, screen split out

Namespaces were shared across features: `settings` was written by core, the
panel and touch, and `input` by touch and buttons. That made "does this
firmware implement the whole feature?" a question no pointer could answer.

Each namespace now belongs to exactly one feature or to core, so a feature is
a provider pointer and the compiler validates completeness:

  gui, node       -> screen, tree, under the screen feature
  settings        -> screen (rotation, theme), sys (timezone),
                     touch (calibration)
  input           -> touch, buttons

Runtime::open() no longer requires a GuiProvider; a firmware without one runs
with no screen/tree globals and reports sys.hasFeature("screen") false.
Rotation is one value again: GuiProvider::setRotation applies and persists, so
an app rotating the panel transiently puts the old value back itself.

lua/lib/hints.lua

@@ -8,8 +8,8 @@ local ORDER = { "back", "left", "up", "down", "right", "confirm" }
 
 local function available()
   local roles = {}
-  if input and input.getButtons then
-    for _, role in ipairs(input.getButtons()) do
+  if buttons and buttons.getAll then
+    for _, role in ipairs(buttons.getAll()) do
       roles[role] = true
     end
   end
@@ -21,11 +21,11 @@ end
 ---@param options table|nil `y`, `font`, `color`, and `background` overrides.
 function hints.draw(actions, options)
   options = options or {}
-  local font = options.font or gui.FONT_SMALL
-  local color = options.color or gui.color(0, 0, 0)
-  local background = options.background or gui.color(255, 255, 255)
-  local height = gui.getFontHeight(font) + 6
-  local y = options.y or (gui.getHeight() - height)
+  local font = options.font or screen.FONT_SMALL
+  local color = options.color or screen.color(0, 0, 0)
+  local background = options.background or screen.color(255, 255, 255)
+  local height = screen.getFontHeight(font) + 6
+  local y = options.y or (screen.getHeight() - height)
 
   local roles = available()
   local labels = {}
@@ -35,15 +35,15 @@ function hints.draw(actions, options)
     end
   end
 
-  gui.fillRect(0, y, gui.getWidth(), height, background)
+  screen.fillRect(0, y, screen.getWidth(), height, background)
   if #labels == 0 then
     return height
   end
 
-  local slot = gui.getWidth() // #labels
+  local slot = screen.getWidth() // #labels
   for index, label in ipairs(labels) do
-    local left = slot * (index - 1) + (slot - gui.getTextWidth(font, label)) // 2
-    gui.drawText(font, left, y + 3, label, color, gui.STYLE_NORMAL, background)
+    local left = slot * (index - 1) + (slot - screen.getTextWidth(font, label)) // 2
+    screen.drawText(font, left, y + 3, label, color, screen.STYLE_NORMAL, background)
   end
   return height
 end

lua/lib/ui.lua

@@ -69,7 +69,7 @@ local function mix(a, b, amount)
 end
 
 local function color(rgb)
-  return gui.color(rgb[1], rgb[2], rgb[3])
+  return screen.color(rgb[1], rgb[2], rgb[3])
 end
 
 local function palette(seed)
@@ -115,27 +115,27 @@ function ui.setTheme(name)
   if not THEMES[name] then
     return nil, "Unknown theme"
   end
-  local ok, err = settings.setTheme(name)
+  local ok, err = screen.setTheme(name)
   if not ok then
     return nil, err
   end
   loadTheme(name)
   if root then
     applyPalette(root)
-    gui.clear(ui.theme.background)
-    node.invalidate(root)
+    screen.clear(ui.theme.background)
+    tree.invalidate(root)
   end
   return true
 end
 
-loadTheme(settings.getTheme())
+loadTheme(screen.getTheme())
 
 local function clearState()
   enterHandlers, exitHandlers, clickHandlers, painters = {}, {}, {}, {}
   pressStyles = {}
 end
 
-node.setPainter(function(id, x, y, w, h)
+tree.setPainter(function(id, x, y, w, h)
   local painter = painters[id]
   if painter then
     painter(id, x, y, w, h)
@@ -166,7 +166,7 @@ local function applyStyle(id, spec)
     style.background, style.fill, hasStyle = spec.background, spec.background, true
   end
   if hasStyle then
-    node.setStyle(id, style)
+    tree.setStyle(id, style)
   end
 end
 
@@ -186,9 +186,9 @@ local function build(spec, kind)
 
   spec.type = kind
   spec.interactive = spec.on_enter ~= nil or spec.on_exit ~= nil or spec.on_click ~= nil
-  local id = node.create(nil, spec)
+  local id = tree.create(nil, spec)
   for _, child in ipairs(children) do
-    node.attach(id, child)
+    tree.attach(id, child)
   end
 
   applyStyle(id, spec)
@@ -234,7 +234,7 @@ end
 ---@return integer w
 ---@return integer h
 function ui.frame()
-  return gui.getWidth(), gui.getHeight() - inset
+  return screen.getWidth(), screen.getHeight() - inset
 end
 
 ---@param spec UiSpec
@@ -259,15 +259,15 @@ end
 ---@return NodeId
 function ui.label(text, spec)
   spec = spec or {}
-  local font, style = spec.font or gui.FONT_UI, spec.style or gui.STYLE_NORMAL
-  if spec.fit and gui.getTextWidth(font, text, style) > spec.fit then
-    while #text > 1 and gui.getTextWidth(font, text .. "~", style) > spec.fit do
+  local font, style = spec.font or screen.FONT_UI, spec.style or screen.STYLE_NORMAL
+  if spec.fit and screen.getTextWidth(font, text, style) > spec.fit then
+    while #text > 1 and screen.getTextWidth(font, text .. "~", style) > spec.fit do
       text = text:sub(1, -2)
     end
     text = text .. "~"
   end
-  spec.w = gui.getTextWidth(font, text, style)
-  spec.h = gui.getFontHeight(font, style)
+  spec.w = screen.getTextWidth(font, text, style)
+  spec.h = screen.getFontHeight(font, style)
   spec.font, spec.fit = font, nil
   return ui.text(text, spec)
 end
@@ -282,7 +282,7 @@ function ui.button(spec)
   spec.label = nil
   local id = build(spec, "button")
   if label then
-    node.create(id, { type = "text", label = label, font = font or gui.FONT_UI })
+    tree.create(id, { type = "text", label = label, font = font or screen.FONT_UI })
   end
   return id
 end
@@ -296,16 +296,16 @@ end
 ---@param id NodeId
 ---@param text string
 function ui.setText(id, text)
-  if node.getLabel(id) == text then
+  if tree.getLabel(id) == text then
     return
   end
-  node.setLabel(id, text)
-  node.invalidate(id)
+  tree.setLabel(id, text)
+  tree.invalidate(id)
 end
 
 ---@param id NodeId
 function ui.invalidate(id)
-  node.invalidate(id)
+  tree.invalidate(id)
 end
 
 ---@param spec UiConfirmSpec
@@ -343,7 +343,7 @@ function ui.confirm(spec)
 end
 
 function ui.reset()
-  node.reset()
+  tree.reset()
   clearState()
   laidOut = false
   root, captured, insideCaptured, confirming = nil, nil, nil, nil
@@ -352,7 +352,7 @@ end
 applyPalette = function(root)
   -- The root is the panel background, not a card: no border, so it takes the fast fillRect
   -- path rather than the per-pixel roundRect one. Radius stays so cards inherit it.
-  node.setStyle(root, {
+  tree.setStyle(root, {
     color = ui.theme.color,
     background = ui.theme.background,
     face = ui.theme.face,
@@ -360,7 +360,7 @@ applyPalette = function(root)
     pressedColor = ui.theme.pressedColor,
     focusColor = ui.theme.focusColor,
     radius = ui.theme.radius,
-    font = gui.FONT_UI,
+    font = screen.FONT_UI,
   })
 end
 
@@ -376,16 +376,16 @@ end
 function ui.rebuild()
   ui.reset()
   root = builder()
-  node.setSize(root, "fill", "fill")
+  tree.setSize(root, "fill", "fill")
   applyPalette(root)
-  local ok, err = node.layout(root, 0, 0, gui.getWidth(), gui.getHeight())
+  local ok, err = tree.layout(root, 0, 0, screen.getWidth(), screen.getHeight())
   if not ok then
     error(err, 2)
   end
-  node.dropScratch()
+  tree.dropScratch()
   laidOut = true
-  gui.clear(ui.theme.background)
-  node.draw(root)
+  screen.clear(ui.theme.background)
+  tree.draw(root)
   -- A build allocates a spec table per node and drops them all here, and the next thing an
   -- app does may be the one that needs a contiguous WiFi buffer. Collecting now costs a few
   -- milliseconds on a screen change nobody can see, and leaves the heap in a known state
@@ -395,18 +395,18 @@ end
 
 function ui.draw()
   if root then
-    node.draw(root)
+    tree.draw(root)
   end
 end
 
 local function inside(id, x, y)
-  local rx, ry, rw, rh = node.getRect(id)
+  local rx, ry, rw, rh = tree.getRect(id)
   return x >= rx and x < rx + rw and y >= ry and y < ry + rh
 end
 
 local function enter(id, x, y)
   if pressStyles[id] then
-    node.setPressed(id, true)
+    tree.setPressed(id, true)
   end
   local handler = enterHandlers[id]
   if handler then
@@ -416,7 +416,7 @@ end
 
 local function exit(id, x, y)
   if pressStyles[id] then
-    node.setPressed(id, false)
+    tree.setPressed(id, false)
   end
   local handler = exitHandlers[id]
   if handler then
@@ -428,16 +428,16 @@ end
 ---@param y integer
 ---@return boolean handled
 function ui.down(x, y)
-  local focused = node.getFocus()
+  local focused = tree.getFocus()
   if focused then
-    node.setFocus(nil)
+    tree.setFocus(nil)
     local handler = exitHandlers[focused]
     if handler then
       handler(focused)
     end
   end
 
-  local target = root and node.hit(root, x, y)
+  local target = root and tree.hit(root, x, y)
   if not target then
     return false
   end
@@ -489,7 +489,7 @@ end
 local DIRECTIONS = { up = true, down = true, left = true, right = true }
 
 local function focusFirst()
-  local focused = node.focusFirst(root)
+  local focused = tree.focusFirst(root)
   if focused then
     local handler = enterHandlers[focused]
     if handler then
@@ -511,12 +511,12 @@ function ui.buttonPress(name, pressed)
     if not pressed then
       return true
     end
-    local previous = node.getFocus()
+    local previous = tree.getFocus()
     if not previous then
       focusFirst()
       return true
     end
-    local focused = node.moveFocus(root, name)
+    local focused = tree.moveFocus(root, name)
     if focused ~= previous then
       local leave = exitHandlers[previous]
       if leave then
@@ -533,18 +533,18 @@ function ui.buttonPress(name, pressed)
   if name ~= "confirm" then
     return false
   end
-  local focused = node.getFocus() or focusFirst()
+  local focused = tree.getFocus() or focusFirst()
   if not focused then
     return false
   end
   if pressed then
-    node.setPressed(focused, true)
+    tree.setPressed(focused, true)
     confirming = focused
   else
     local target = confirming
     confirming = nil
     if target then
-      node.setPressed(target, false)
+      tree.setPressed(target, false)
       local handler = clickHandlers[target]
       if handler then
         handler(target)