test(oauth-client): full interactive pipeline snapshot test (AC8.7)
Add full_pipeline_interactive_all_pass test to oauth_client_endtoend.rs that
exercises the interactive stage with DriveRpInProcess mode. The test spawns a
fake AS and drives a deterministic RP through the OAuth flow, capturing all
interactive stage check IDs in the snapshot for AC8.7 regression baseline.
This completes the critical missing piece where interactive checks were
implemented in code but never actually captured in snapshots. The snapshot now
contains oauth_client::interactive check IDs, making the check_id_coverage test
meaningful rather than self-satisfying.
The test captures Phase 7 interactive checks with their diagnostic codes:
- oauth_client::interactive::server_bound
- oauth_client::interactive::client_reached_par
- oauth_client::interactive::client_used_pkce_s256
- oauth_client::interactive::client_included_dpop
- oauth_client::interactive::client_completed_token
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>