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.

native/include/lua/runtime.h

@@ -128,6 +128,7 @@ class Runtime {
   bool loadScript(const std::string& path);
   void installLoader(const std::string& appDir);
   static int searchModule(lua_State* state);
+  static int searchEmbedded(lua_State* state);
   static int loadFile(lua_State* state);
 
   // A batch is one visit to the app, however many callbacks it fans out into: a tap fires