docs(auth): document user_id convention and write-path shape

After the UiAuth / Oidc / UserAdmin controllers were aligned to store
bare user_ids, the rules that future sessions read were still describing
the old behaviour (OutboundConnectionAdminController "strips user:
prefix" — true mechanically but the subtlety is that the strip is
the bridge between a prefixed JWT subject and an unprefixed DB key,
not a hack).

- CLAUDE.md: expand the User persistence one-liner to state the
  convention authoritatively (local `<username>`, OIDC `oidc:<sub>`,
  JWT `user:` namespace, env-scoped controllers strip for FK).
- .claude/rules/app-classes.md:
  - Add "User ID conventions" section near the top that spells out
    write-path vs read-path behaviour in one place.
  - Add UiAuthController + OidcAuthController entries under
    security/ with their upsert shape documented.
  - Soften the OutboundConnectionAdminController line to reference
    the convention instead of restating the mechanism.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -51,7 +51,7 @@ java -jar cameleer-server-app/target/cameleer-server-app-1.0-SNAPSHOT.jar
 - OIDC: Optional external identity provider support (token exchange pattern). Configured via admin API/UI, stored in database (`server_config` table). Resource server mode: accepts external access tokens (Logto M2M) via JWKS validation when `CAMELEER_SERVER_SECURITY_OIDCISSUERURI` is set. Scope-based role mapping via `SystemRole.normalizeScope()`. System roles synced on every OIDC login via `applyClaimMappings()` in `OidcAuthController` (calls `clearManagedAssignments` + `assignManagedRole` on `RbacService`) — always overwrites managed role assignments; uses managed assignment origin to avoid touching group-inherited or directly-assigned roles. Supports ES384, ES256, RS256.
 - OIDC role extraction: `OidcTokenExchanger` reads roles from the **access_token** first (JWT with `at+jwt` type), then falls back to id_token. `OidcConfig` includes `audience` (RFC 8707 resource indicator) and `additionalScopes`. All provider-specific configuration is external — no provider-specific code in the server.
 - Sensitive keys: Global enforced baseline for masking sensitive data in agent payloads. Merge rule: `final = global UNION per-app` (case-insensitive dedup, per-app can only add, never remove global keys).
-- User persistence: PostgreSQL `users` table, admin CRUD at `/api/v1/admin/users`
+- User persistence: PostgreSQL `users` table, admin CRUD at `/api/v1/admin/users`. `users.user_id` is the **bare** identifier — local users as `<username>`, OIDC users as `oidc:<sub>`. JWT `sub` carries the `user:` namespace prefix so `JwtAuthenticationFilter` can tell user tokens from agent tokens; write paths (`UiAuthController`, `OidcAuthController`, `UserAdminController`) all upsert unprefixed, and env-scoped read-path controllers strip the `user:` prefix before using the value as an FK to `users.user_id` / `user_roles.user_id`. Alerting / outbound FKs (`alert_rules.created_by`, `outbound_connections.created_by`, …) therefore all reference the bare form.
 - Usage analytics: ClickHouse `usage_events` table tracks authenticated UI requests, flushed every 5s
 
 ## Database Migrations