GET /auth/oauth/{provider}/web-callback receives the Google redirect and
bounces immediately to adiuvai://oauth/callback deep link. Google Cloud
Console only accepts http/https redirect URIs — adiuvai:// is not valid.
Default OAUTH_REDIRECT_URI now points to localhost:8000 for dev; override
with the API domain env var in production.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>