fix: move Application instantiation to module level and increase gunicorn workers to 4

Move the `Application` instance creation from inside the async `main()` function to module scope in `src/snek/app.py`, ensuring the app object is available at import time for gunicorn's worker initialization. In `compose.yml`, increase the gunicorn worker count from 1 to 4 to improve concurrent request handling under the aiohttp worker class.

src/snek/app.py

@@ -127,8 +127,10 @@ class Application(BaseApplication):
         return await super().render_template(template, request, context)
 
 
+
+app = Application(db_path="sqlite:///snek.db")
+
 async def main():
-    app = Application(db_path="sqlite:///snek.db")
     await web._run_app(app, port=8081, host="0.0.0.0")
 
 if __name__ == "__main__":