Add serial upload tool for rapid Lua game iteration

Implements a complete serial upload workflow that allows uploading and
immediately testing Lua games via USB serial connection.

New Components:
- SerialUploader: Receives files via serial, writes to SD card
- upload_game.py: Python tool for sending files from host computer
- Protocol: Text-based with base64 encoding for reliability

Key Features:
- Uploads file to /games folder on SD card
- Overwrites existing files (FA_CREATE_ALWAYS)
- Auto-launches uploaded game immediately
- Proper memory cleanup (prevents Lua state conflicts)

SD Card Fixes:
- Fixed SPI speed management (12.5MHz for SD, 32MHz for display)
- Fixed SD write protocol (poll for data response token)
- Added speed switching wrappers around all FatFS operations
- Cleaned up excessive debug output

Game Launcher Improvements:
- Added clear_games() to prevent duplicate registrations
- Added cleanup in select_game_by_name() to delete old instances
- Added exact match priority in game selection
- LuaGameLoader now has clear_factory_data() for memory cleanup

Integration:
- Added serial_uploader to CMakeLists.txt
- Integrated into main loop in basic1.cpp
- Re-scans games after upload to pick up new files

Documentation:
- UPLOAD_TOOL.md: Usage instructions
- sd_card_best_practices.md: Critical lessons learned

Known Issues:
- Game launch after upload occasionally causes freeze (needs investigation)
- Display may not refresh properly after upload

Usage:
  python upload_game.py games/lua_examples/2048.lua /dev/tty.usbmodem101

Co-Authored-By: Claude <noreply@anthropic.com>

games/lua_game_loader.cpp

@@ -23,6 +23,15 @@ struct LuaGameFactoryData {
 
 static std::vector<LuaGameFactoryData*> factory_data_list;
 
+void LuaGameLoader::clear_factory_data() {
+    // Delete all factory data and clear the vector
+    for (LuaGameFactoryData* data : factory_data_list) {
+        delete data;
+    }
+    factory_data_list.clear();
+    printf("LuaGameLoader: Cleared all factory data\n");
+}
+
 // Factory wrapper that captures script path
 static Game* lua_game_factory_wrapper(uint16_t width, uint16_t height,
                                        LowLevelRenderer* renderer, LowLevelGUI* gui,