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>

lib/game_launcher.cpp

@@ -8,6 +8,7 @@
 #include "display/low_level_render.h"
 #include "display/low_level_gui.h"
 #include <stdio.h>
+#include <cstring>
 
 GameLauncher::GameLauncher(uint16_t width, uint16_t height, 
                           LowLevelRenderer* renderer, LowLevelGUI* gui, InputManager* input_manager)
@@ -212,6 +213,72 @@ void GameLauncher::reset() {
     printf("Launcher reset - returning to menu\n");
 }
 
+void GameLauncher::clear_games() {
+    // Clean up currently selected game first
+    if (selected_game) {
+        delete selected_game;
+        selected_game = nullptr;
+    }
+
+    // Clear the games vector
+    games.clear();
+    selected_index = 0;
+    current_page = 0;
+    printf("Launcher: Cleared all registered games\n");
+}
+
+bool GameLauncher::select_game_by_name(const char* name) {
+    // Clean up old game first if one exists
+    if (selected_game) {
+        printf("Cleaning up previous game...\n");
+        delete selected_game;
+        selected_game = nullptr;
+    }
+
+    // First pass: search for exact match (prefer exact matches)
+    for (size_t i = 0; i < games.size(); i++) {
+        if (strcmp(games[i].name, name) == 0) {
+            printf("Found exact match: %s\n", games[i].name);
+
+            // Create and initialize the game
+            selected_game = games[i].factory(width, height, renderer, gui, input_manager);
+            if (selected_game) {
+                printf("Game instance created, initializing...\n");
+                selected_game->init();
+                selected_index = i;
+                current_page = i / GAMES_PER_PAGE;
+                return true;
+            } else {
+                printf("Failed to create game instance\n");
+                return false;
+            }
+        }
+    }
+
+    // Second pass: search in reverse order for partial match (newest files first)
+    for (int i = games.size() - 1; i >= 0; i--) {
+        if (strstr(games[i].name, name) != nullptr) {
+            printf("Found partial match: %s (searching for: %s)\n", games[i].name, name);
+
+            // Create and initialize the game
+            selected_game = games[i].factory(width, height, renderer, gui, input_manager);
+            if (selected_game) {
+                printf("Game instance created, initializing...\n");
+                selected_game->init();
+                selected_index = i;
+                current_page = i / GAMES_PER_PAGE;
+                return true;
+            } else {
+                printf("Failed to create game instance\n");
+                return false;
+            }
+        }
+    }
+
+    printf("Game not found: %s\n", name);
+    return false;
+}
+
 int GameLauncher::get_total_pages() const {
     if (games.empty()) return 1;
     return (games.size() + GAMES_PER_PAGE - 1) / GAMES_PER_PAGE;