feat: comprehensive test infrastructure improvements

- Fix unit test imports: add env setup in conftest.py before module imports
- Add 24 new auth router tests (RBAC, preferences, password validation)
- Add 16 new tests for litellm and chat_summary routers
- Apply black formatting and ruff linting across codebase
- Add pre-commit hooks configuration (black, ruff, file checks)
- Increase CI coverage threshold from 40% to 50%

Test Results:
- 206 tests passing (91 unit + 115 integration)
- Coverage: 58.79% on core modules
- auth.py: 57% → 85%, litellm.py: 23% → 87%, chat_summary.py: 41% → 100%
- auth_service: 96.51%, config: 100%, rbac: 93.48%

dashboard/backend/config.py

@@ -1,6 +1,8 @@
-import os
 import ipaddress
+import os
+
 from fastapi import Request
+
 # Dashboard v1.3 — Runner DNS fix applied
 
 GITEA_URL = os.environ.get("GITEA_URL", "http://gitea:3000")
@@ -42,7 +44,9 @@ TELEGRAM_CHAT_ID = os.environ.get("TELEGRAM_CHAT_ID", "")
 TELEGRAM_PROXY = os.environ.get("TELEGRAM_PROXY", "")
 
 WEBAUTHN_RP_ID = os.environ.get("WEBAUTHN_RP_ID", "jimmygan.com")
-WEBAUTHN_ORIGINS = os.environ.get("WEBAUTHN_ORIGINS", "https://nas.jimmygan.com,https://nas.jimmygan.com:8443").split(",")
+WEBAUTHN_ORIGINS = os.environ.get("WEBAUTHN_ORIGINS", "https://nas.jimmygan.com,https://nas.jimmygan.com:8443").split(
+    ","
+)
 
 # CORS
 CORS_ORIGINS = os.environ.get("CORS_ORIGINS", "https://nas.jimmygan.com,https://nas.jimmygan.com:8443").split(",")