bug: OAuth-authenticated users lose API access after every server restart

[piyushdotcomm]

Bug Description

When a user logs in via GitHub or Google OAuth for the first time, their generated API key is saved to the database and added to the in-memory settings.API_KEYS dictionary. This works correctly during that session.

However, after a server restart, settings.API_KEYS is only repopulated from the API_KEYS environment variable. It does NOT reload previously approved OAuth users from the database.

Since verify_api_key() validates all incoming API keys against settings.API_KEYS (in-memory only), every OAuth user gets a 401 Invalid API key response after any restart or redeployment.

Steps to Reproduce

1. Log in via GitHub or Google OAuth — works correctly.
2. Make an API request to /ask — returns a valid response.
3. Restart the server.
4. Make the same API request with the same key — returns 401 Invalid API key.

Root Cause

sync_env_keys_to_db() only syncs keys from the .env file into the database. It never reads all approved keys back from the database into memory. OAuth-created keys exist in the database but are invisible to the API key validator after a restart.

Suggested Fix

In main.py, after calling sync_env_keys_to_db(db):

approved_keys = db.query(APIKey).filter(
    APIKey.approved == True,
    APIKey.is_active == True
).all()
for key_obj in approved_keys:
    settings.API_KEYS[key_obj.key] = {
        "name": key_obj.name,
        "can_change_model": key_obj.can_change_model
    }