Add Lua 5.4 scripting integration for dynamic game loading

- Integrated Lua 5.4 engine (32-bit mode for embedded ARM)
- Created LuaGame wrapper class implementing Game interface
- Added C++ bindings exposing renderer, game state, and input to Lua
- Implemented SD card loader for automatic .lua game discovery
- Updated GameLauncher to support std::function for lambda captures
- Made Game class members public for Lua bindings access
- Added example Lua games: counter, snake, bouncing ball
- Included comprehensive API documentation

Games can now be written as .lua text files on SD card and loaded
without recompilation. Build size: 747KB UF2, Lua VM uses ~50-80KB RAM.

games/lua_game_loader.cpp

@@ -0,0 +1,164 @@
+// ============================================================================
+// LUA GAME LOADER - IMPLEMENTATION
+// ============================================================================
+// Discovers Lua scripts on SD card and integrates with game launcher
+
+#include "lua_game_loader.h"
+#include "lua_game.h"
+#include <stdio.h>
+#include <string.h>
+#include <vector>
+
+extern "C" {
+    #include "ff.h"
+}
+
+// Structure to hold script path for factory closure
+struct LuaGameFactoryData {
+    char script_path[256];
+};
+
+static std::vector<LuaGameFactoryData*> factory_data_list;
+
+// Factory wrapper that captures script path
+static Game* lua_game_factory_wrapper(uint16_t width, uint16_t height,
+                                       LowLevelRenderer* renderer, LowLevelGUI* gui,
+                                       InputManager* input_manager, void* user_data) {
+    LuaGameFactoryData* data = (LuaGameFactoryData*)user_data;
+    return new LuaGame(data->script_path, width, height, renderer, gui, input_manager);
+}
+
+bool LuaGameLoader::parse_metadata(const char* script_path, char* name, char* description) {
+    FIL fil;
+    FRESULT fr;
+    
+    // Default name from filename
+    const char* filename = strrchr(script_path, '/');
+    if (filename) {
+        filename++;
+    } else {
+        filename = script_path;
+    }
+    
+    // Remove .lua extension for default name
+    strncpy(name, filename, 63);
+    name[63] = '\0';
+    char* ext = strstr(name, ".lua");
+    if (ext) *ext = '\0';
+    
+    // Default empty description
+    description[0] = '\0';
+    
+    // Try to open file and parse metadata comments
+    fr = f_open(&fil, script_path, FA_READ);
+    if (fr != FR_OK) {
+        printf("LuaGameLoader: Warning - could not open %s for metadata\n", script_path);
+        return false;
+    }
+    
+    // Read first 512 bytes to look for metadata comments
+    char buffer[512];
+    UINT bytes_read;
+    fr = f_read(&fil, buffer, sizeof(buffer) - 1, &bytes_read);
+    f_close(&fil);
+    
+    if (fr != FR_OK) {
+        return false;
+    }
+    
+    buffer[bytes_read] = '\0';
+    
+    // Parse metadata comments: -- NAME: Game Name
+    char* line = buffer;
+    while (line && (line - buffer) < bytes_read) {
+        char* next_line = strchr(line, '\n');
+        if (next_line) *next_line = '\0';
+        
+        // Check for -- NAME: 
+        if (strncmp(line, "-- NAME:", 8) == 0) {
+            const char* value = line + 8;
+            while (*value == ' ') value++;  // Skip spaces
+            strncpy(name, value, 63);
+            name[63] = '\0';
+        }
+        // Check for -- DESC:
+        else if (strncmp(line, "-- DESC:", 8) == 0) {
+            const char* value = line + 8;
+            while (*value == ' ') value++;
+            strncpy(description, value, 127);
+            description[127] = '\0';
+        }
+        
+        if (next_line) {
+            line = next_line + 1;
+        } else {
+            break;
+        }
+    }
+    
+    return true;
+}
+
+int LuaGameLoader::register_all_games(GameLauncher* launcher) {
+    DIR dir;
+    FILINFO fno;
+    FRESULT fr;
+    int count = 0;
+    
+    printf("LuaGameLoader: Scanning /games directory for .lua scripts...\n");
+    
+    // Open /games directory
+    fr = f_opendir(&dir, "/games");
+    if (fr != FR_OK) {
+        printf("LuaGameLoader: Could not open /games directory (error %d)\n", fr);
+        printf("LuaGameLoader: Make sure SD card is mounted and /games exists\n");
+        return 0;
+    }
+    
+    // Scan for .lua files
+    while (true) {
+        fr = f_readdir(&dir, &fno);
+        if (fr != FR_OK || fno.fname[0] == 0) break;  // End of directory
+        
+        // Skip directories
+        if (fno.fattrib & AM_DIR) continue;
+        
+        // Check for .lua extension
+        size_t len = strlen(fno.fname);
+        if (len < 5 || strcmp(fno.fname + len - 4, ".lua") != 0) continue;
+        
+        // Build full path
+        char script_path[256];
+        snprintf(script_path, sizeof(script_path), "/games/%s", fno.fname);
+        
+        // Parse metadata
+        char name[64];
+        char description[128];
+        parse_metadata(script_path, name, description);
+        
+        printf("LuaGameLoader: Found %s - '%s'\n", fno.fname, name);
+        
+        // Create factory data (persistent for game lifetime)
+        LuaGameFactoryData* data = new LuaGameFactoryData();
+        strncpy(data->script_path, script_path, sizeof(data->script_path) - 1);
+        data->script_path[sizeof(data->script_path) - 1] = '\0';
+        factory_data_list.push_back(data);
+        
+        // Register with launcher - using lambda factory pattern
+        launcher->register_game(
+            name,
+            description[0] ? description : "Lua Script",
+            [data](uint16_t width, uint16_t height, LowLevelRenderer* renderer, 
+                   LowLevelGUI* gui, InputManager* input_manager) -> Game* {
+                return new LuaGame(data->script_path, width, height, renderer, gui, input_manager);
+            }
+        );
+        
+        count++;
+    }
+    
+    f_closedir(&dir);
+    
+    printf("LuaGameLoader: Registered %d Lua games\n", count);
+    return count;
+}