feat: Add dummy game utility and enhance testing capabilities

- also improve argument handling

src/dummy_game.c

@@ -0,0 +1,67 @@
+#include <SDL2/SDL.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[]) {
+    int delay_seconds = 5;
+    if (argc > 1) {
+        int parsed = atoi(argv[1]);
+        if (parsed > 0) {
+            delay_seconds = parsed;
+        }
+    }
+
+    printf("[dummy_game] Simulating engine startup for %d seconds...\n", delay_seconds);
+    for (int i = 0; i < delay_seconds; i++) {
+        sleep(1);
+        printf("[dummy_game] Loading... %d/%d\n", i + 1, delay_seconds);
+    }
+
+    printf("[dummy_game] Creating window to trigger focus-loss on splash screen...\n");
+    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+        fprintf(stderr, "[dummy_game] SDL Init Failed: %s\n", SDL_GetError());
+        return 1;
+    }
+
+    SDL_Window *window = SDL_CreateWindow(
+        "Dummy Game Window",
+        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+        800, 600,
+        SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE
+    );
+
+    if (!window) {
+        fprintf(stderr, "[dummy_game] Window Creation Failed: %s\n", SDL_GetError());
+        SDL_Quit();
+        return 1;
+    }
+
+    SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
+    if (renderer) {
+        SDL_SetRenderDrawColor(renderer, 0, 120, 255, 255);
+        SDL_RenderClear(renderer);
+        SDL_RenderPresent(renderer);
+    }
+
+    printf("[dummy_game] Window created. Waiting 5 seconds before exiting...\n");
+
+    SDL_Event event;
+    int running = 1;
+    Uint32 start_time = SDL_GetTicks();
+    
+    while (running && (SDL_GetTicks() - start_time < 5000)) {
+        while (SDL_PollEvent(&event)) {
+            if (event.type == SDL_QUIT) {
+                running = 0;
+            }
+        }
+        SDL_Delay(50);
+    }
+
+    printf("[dummy_game] Exiting normally.\n");
+    if (renderer) SDL_DestroyRenderer(renderer);
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+    return 0;
+}

src/gsplash.c

@@ -317,8 +317,14 @@ int main(int argc, char *argv[])
         render_mode = parse_render_mode(argv[1] + 7);
         arg_index += 1;
     }
-    else if (argc >= 4 && strcmp(argv[1], "-m") == 0)
+    else if (argc >= 2 && strcmp(argv[1], "-m") == 0)
     {
+        if (argc < 4)
+        {
+            log_error("Usage: %s [--mode=stretch|center|crop] <image_path> <game_executable> [args...]", argv[0]);
+            log_error("       %s -m stretch|center|crop <image_path> <game_executable> [args...]", argv[0]);
+            return 1;
+        }
         render_mode = parse_render_mode(argv[2]);
         arg_index += 2;
     }
@@ -333,7 +339,7 @@ int main(int argc, char *argv[])
     const char *image_path = argv[arg_index];
     const char *game_path = argv[arg_index + 1];
 
-    log_info("Starting splash: image='%s', game='%s'", image_path, game_path);
+    log_info("Starting splash: image='%s', game='%s', mode=%d", image_path, game_path, render_mode);
 
     // Initialize SDL2 Video subsystems
     if (SDL_Init(SDL_INIT_VIDEO) < 0)