Live import (X OAuth 2.0 PKCE) requires paid API tier for bookmarks

[shaal]

Problem

The Live Import tab on the import page references X OAuth 2.0 PKCE for importing bookmarks, but:

1. The backend OAuth routes don't exist — clicking "Connect X Account" returns an HTML 404 parsed as JSON, causing Unexpected token '<' errors.

2. X OAuth credentials can only be stored in the database via the Settings UI — there's no support for environment variables (X_OAUTH_CLIENT_ID, X_OAUTH_CLIENT_SECRET), which is inconsistent with how ANTHROPIC_API_KEY / ANTHROPIC_BASE_URL work.

3. Even once connected, the X API v2 GET /2/users/:id/bookmarks endpoint requires a paid API plan (Basic at $200/month). Free-tier developer accounts get: Your enrolled account does not have any credits to fulfill this request.

This makes the Live Import tab effectively non-functional for most users.

Expected behavior

• The OAuth flow should work end-to-end (authorize → callback → token exchange → fetch bookmarks)
• X OAuth credentials should be configurable via environment variables
• The UI should clearly communicate the paid-tier requirement before users go through the setup