Server: Add launcher version scanning on startup

- Scan versions/ directory and generate meta.json for each version
- Log progress: 'Scanning launcher versions...', 'Launcher meta ready: vX (Y files)'
- Meta cached in memory for faster access

server/main.py

@@ -147,6 +147,17 @@ async def lifespan(app: FastAPI):
                 logger.error(f"Failed to scan pack: {pack_dir.name} - {e}", exc_info=True)
     
     logger.info("All packs ready. Server is running.")
+    
+    # Scan launcher versions and generate meta
+    logger.info("Scanning launcher versions...")
+    launcher_versions = get_launcher_versions()
+    if launcher_versions:
+        latest = launcher_versions[0]
+        logger.info(f"Launcher meta ready: v{latest['meta']['version']} ({len(latest['meta']['files'])} files)")
+    else:
+        logger.warning("No launcher versions found in new format")
+    
+    logger.info("Launcher meta system ready.")
 
     # Initialize proxy client
     global proxy_client