Cherry-picked from decolua/9router PR #183.
Note: open-sse changes included but need further review due to extensive modifications.
Co-authored-by: Cursor <cursoragent@cursor.com>
- Add CursorExecutor for handling requests to the Cursor API using protobuf over HTTP/2.
- Implement CursorAuthModal for user token import from local SQLite database.
- Update provider models and constants to include Cursor as a supported provider.
- Enhance API service with token validation and user info extraction from Cursor tokens.
- Introduce utility functions for checksum generation and protobuf encoding/decoding for Cursor API interactions.