## Why

The project has database foundations in place but still lacks production-ready user authentication. We need a secure OAuth2/OIDC integration with Authentik that issues internal session credentials and supports reliable logout and token revocation.

## What Changes

- Implement backend OAuth2/OIDC login and callback flow against Authentik.
- Verify Authentik-issued tokens via JWKS before minting local credentials.
- Mint short-lived internal JWT access tokens and store refresh tokens server-side.
- Add refresh-token rotation, revocation, and explicit logout semantics.
- Apply environment-aware secure cookie policy (strict in production, relaxed for localhost development).
- Add auth endpoints, supporting services, and test coverage for auth flows.

## Capabilities

### New Capabilities
- `auth-session-tokens`: Internal JWT access-token issuance, opaque refresh-token storage, rotation, and revocation.

### Modified Capabilities
- `auth-oauth`: Extend OAuth/OIDC behavior to require JWKS validation, internal JWT minting, cookie policy by environment, and DB-backed refresh lifecycle.

## Impact

- Affected backend modules in `apps/api/src` (config, models, auth services, API routes).
- New database schema object for refresh-token persistence and an accompanying migration.
- New environment variables for OIDC/JWT/cookie settings.
- Frontend auth integration points for login/logout/me/refresh behavior.
