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/api/features/screen/screen.lua

@@ -0,0 +1,164 @@
+---@meta
+
+-- Generated from native/src/bindings/features/screen/screen.cpp. Do not edit.
+
+-- The panel itself; the widget tree it paints is `tree`, and
+-- sys.hasFeature("screen") covers both.
+---@alias ScreenColor integer
+---@alias ScreenFont integer
+---@alias ScreenTextStyle integer
+
+---@class ScreenLib
+---@field FONT_SMALL ScreenFont Small auxiliary text.
+---@field FONT_UI ScreenFont Normal controls and labels.
+---@field FONT_BODY ScreenFont Normal reading text.
+---@field FONT_LARGE ScreenFont Headings and prominent values.
+---@field STYLE_NORMAL ScreenTextStyle
+---@field STYLE_BOLD ScreenTextStyle
+screen = {}
+screen.FONT_SMALL = 0
+screen.FONT_UI = 0
+screen.FONT_BODY = 0
+screen.FONT_LARGE = 0
+screen.STYLE_NORMAL = 0
+screen.STYLE_BOLD = 0
+
+---Returns the live frame width.
+---@return integer
+function screen.getWidth() end
+
+---Returns the live frame height.
+---@return integer
+function screen.getHeight() end
+
+---Rotates the panel and persists the choice, so there is one rotation
+---rather than a live one and a saved one to reconcile.
+---@param degrees integer 0, 90, 180, or 270 clockwise.
+---@return true? ok
+---@return string? error
+function screen.setRotation(degrees) end
+
+---Returns the rotation in degrees clockwise.
+---@return integer
+function screen.getRotation() end
+
+---Returns the saved palette name. Apps read ui.getTheme() instead; this
+---is the stored value, which only ui.setTheme() knows how to apply.
+---@return string
+function screen.getTheme() end
+
+---Persists a palette name without applying it. Call ui.setTheme(), which
+---writes through here and then rebuilds the palette and repaints.
+---@param theme string
+---@return true? ok
+---@return string? error
+function screen.setTheme(theme) end
+
+---Returns an opaque native color. E-ink implementations quantize RGB to available grayscale.
+---@param r integer 0 through 255.
+---@param g integer 0 through 255.
+---@param b integer 0 through 255.
+---@return ScreenColor
+function screen.color(r, g, b) end
+
+---Clears the frame.
+---@param color? ScreenColor Defaults to white.
+function screen.clear(color) end
+
+---Fills a rectangle.
+---@param x integer
+---@param y integer
+---@param w integer
+---@param h integer
+---@param color ScreenColor
+function screen.fillRect(x, y, w, h, color) end
+
+---Outlines a rectangle.
+---@param x integer
+---@param y integer
+---@param w integer
+---@param h integer
+---@param color ScreenColor
+function screen.drawRect(x, y, w, h, color) end
+
+---Draws a line.
+---@param x1 integer
+---@param y1 integer
+---@param x2 integer
+---@param y2 integer
+---@param color ScreenColor
+---@param width? integer Defaults to one pixel.
+function screen.drawLine(x1, y1, x2, y2, color, width) end
+
+---Draws a single pixel.
+---@param x integer
+---@param y integer
+---@param color ScreenColor
+function screen.drawPixel(x, y, color) end
+
+---Outlines a circle.
+---@param x integer Center.
+---@param y integer Center.
+---@param radius integer
+---@param color ScreenColor
+---@param width? integer Defaults to one pixel.
+function screen.drawCircle(x, y, radius, color, width) end
+
+---Fills a circle.
+---@param x integer Center.
+---@param y integer Center.
+---@param radius integer
+---@param color ScreenColor
+---@param background? ScreenColor Surface behind an anti-aliased edge.
+function screen.fillCircle(x, y, radius, color, background) end
+
+---Draws an anti-aliased rounded fill, optional gradient, and optional border in one pass.
+---@param x integer
+---@param y integer
+---@param w integer
+---@param h integer
+---@param radius integer
+---@param background ScreenColor Surface behind the anti-aliased edge.
+---@param top? ScreenColor Fill, or gradient top; omitted for no fill.
+---@param bottom? ScreenColor Gradient bottom; defaults to top. Panels without a gradient use top.
+---@param border? ScreenColor Omitted for no border.
+function screen.roundRect(x, y, w, h, radius, background, top, bottom, border) end
+
+---Fills a polygon.
+---@param xs integer[]
+---@param ys integer[]
+---@param color ScreenColor
+function screen.fillPolygon(xs, ys, color) end
+
+---Draws a bitmap.
+---@param path string Absolute BMP path.
+---@param x? integer Left edge; defaults to centered.
+---@param y? integer Top edge; defaults to centered.
+---@param maxWidth? integer Defaults to panel width.
+---@param maxHeight? integer Defaults to panel height.
+---@return true? ok
+---@return string? error
+function screen.drawBmp(path, x, y, maxWidth, maxHeight) end
+
+---Measures a text run.
+---@param font ScreenFont Use a named screen.FONT_* role.
+---@param text string
+---@param style? ScreenTextStyle Defaults to screen.STYLE_NORMAL.
+---@return integer
+function screen.getTextWidth(font, text, style) end
+
+---Returns the line height of a font role.
+---@param font ScreenFont Use a named screen.FONT_* role.
+---@param style? ScreenTextStyle Defaults to screen.STYLE_NORMAL.
+---@return integer
+function screen.getFontHeight(font, style) end
+
+---Draws a text run with its top-left corner at x, y.
+---@param font ScreenFont Use a named screen.FONT_* role.
+---@param x integer Left edge.
+---@param y integer Top edge.
+---@param text string
+---@param color? ScreenColor Defaults to black.
+---@param style? ScreenTextStyle Defaults to screen.STYLE_NORMAL.
+---@param background? ScreenColor Omitted for transparent text.
+function screen.drawText(font, x, y, text, color, style, background) end