Consolidate 16 migrations into one with UUID columns for all entity
IDs. TEXT is kept only for polymorphic fields (audit_logs.actor_id,
resource_id) and template names. The id package now generates UUIDs
via google/uuid, with Format*/Parse* helpers for the prefixed wire
format (sb-{uuid}, usr-{uuid}, etc.). Auth context, services, and
handlers pass pgtype.UUID internally; conversion to/from prefixed
strings happens at API and RPC boundaries. Adds PlatformTeamID
(all-zeros UUID) for shared resources.
Implement OAuth 2.0 login via GitHub as an alternative to email/password.
Uses a provider registry pattern (internal/auth/oauth/) so adding Google
or other providers later requires only a new Provider implementation.
Flow: GET /v1/auth/oauth/github redirects to GitHub, callback exchanges
the code for a user profile, upserts the user + team atomically, and
redirects to the frontend with a JWT token.
Key changes:
- Migration: make password_hash nullable, add oauth_providers table
- Provider registry with GitHubProvider (profile + email fallback)
- CSRF state cookie with HMAC-SHA256 validation
- Race-safe registration (23505 collision retries as login)
- Startup validation: CP_PUBLIC_URL required when OAuth is configured
Not fully tested — needs integration tests with a real GitHub OAuth app
and end-to-end testing with the frontend callback page.
