remove safety during the bigger model initialization

app/main.py

@@ -22,7 +22,7 @@ from google.genai import types
 # something
 API_KEY = os.getenv("GEMINI_API_KEY", "")
 # Switch to 2.5 Flash as requested
-MODEL   = os.getenv("GEMINI_MODEL", "gemini-2.5-flash")
+MODEL   = os.getenv("GEMINI_MODEL")
 SMALL_MODEL = os.getenv("GEMINI_SMALL_MODEL") or MODEL
 PORT    = int(os.getenv("PORT", "7860"))