fix: accept multiple OIDC audiences for cross-client auth

- Changed oidc_audience (string) to oidc_audiences (list)
- Now accepts tokens with audience: core-api, tatlock-ui, tatlock
- Fixes environment endpoint returning "default" user when using
  tatlock-ui token (audience mismatch was causing JWT claims error)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/shared/config.py

@@ -91,7 +91,8 @@ class Settings(BaseSettings):
     # OIDC Authentication (Authentik)
     oidc_enabled: bool = False
     oidc_issuer: str = "https://auth.schweitz.net/application/o/core-api/"
-    oidc_audience: str = "core-api"
+    # Accept tokens from multiple clients (core-api, tatlock-ui, tatlock)
+    oidc_audiences: list[str] = ["core-api", "tatlock-ui", "tatlock"]
 
     # Authentik API (for token validation and user management)
     authentik_url: str = "https://auth.schweitz.net"