feat(runtime): embed platform modules as bytecode

ui.lua and hints.lua are compiled to LUA_32BITS bytecode (matching the
firmware's Lua build) and linked into the binary. A new package.searchers
entry checks them as the fallback after the SD card, so a local
/.lua/lib/ui.lua still shadows the packaged one for debugging.

Bytecode is ~40% smaller than source and loads without parsing. A fresh
SD card with no make sdcard now has the platform available.

tools/dump.c

@@ -0,0 +1,36 @@
+// Dumps a Lua source file as bytecode, linked against the same vendored Lua the firmware
+// runs (LUA_32BITS), so the header matches. Stand-in for luac when only the library is
+// vendored.
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lauxlib.h"
+#include "lua.h"
+
+static int writer(lua_State*, const void* p, size_t size, void* ud) {
+  return fwrite(p, 1, size, (FILE*)ud) != size ? 1 : 0;
+}
+
+int main(int argc, char** argv) {
+  if (argc != 3) {
+    fprintf(stderr, "usage: %s input.lua output.luac\n", argv[0]);
+    return 1;
+  }
+  lua_State* L = luaL_newstate();
+  if (luaL_loadfilex(L, argv[1], "t") != LUA_OK) {
+    fprintf(stderr, "%s: %s\n", argv[1], lua_tostring(L, -1));
+    lua_close(L);
+    return 1;
+  }
+  FILE* out = fopen(argv[2], "wb");
+  if (!out) {
+    fprintf(stderr, "cannot open %s\n", argv[2]);
+    lua_close(L);
+    return 1;
+  }
+  const int err = lua_dump(L, writer, out, 1);  // strip debug info
+  fclose(out);
+  lua_close(L);
+  return err ? 1 : 0;
+}