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/tests/integration/test_gitea.py

@@ -1,6 +1,7 @@
 """
 Integration tests for Gitea operations.
 """
+
 import pytest
 
 
@@ -27,19 +28,13 @@ class TestGiteaCommits:
     @pytest.mark.skip(reason="Requires external Gitea API - tested manually")
     def test_list_commits(self, test_app, admin_headers):
         """Test listing commits for a repository."""
-        response = test_app.get(
-            "/api/gitea/repos/owner/repo/commits",
-            headers=admin_headers
-        )
+        response = test_app.get("/api/gitea/repos/owner/repo/commits", headers=admin_headers)
         # This would require a real Gitea instance
         assert response.status_code in [200, 404, 500, 503]
 
     def test_list_commits_invalid_owner(self, test_app, admin_headers):
         """Test listing commits with invalid owner name."""
-        response = test_app.get(
-            "/api/gitea/repos/invalid@owner/repo/commits",
-            headers=admin_headers
-        )
+        response = test_app.get("/api/gitea/repos/invalid@owner/repo/commits", headers=admin_headers)
 
         assert response.status_code == 400
         data = response.json()
@@ -48,10 +43,7 @@ class TestGiteaCommits:
 
     def test_list_commits_invalid_repo(self, test_app, admin_headers):
         """Test listing commits with invalid repo name."""
-        response = test_app.get(
-            "/api/gitea/repos/owner/invalid@repo/commits",
-            headers=admin_headers
-        )
+        response = test_app.get("/api/gitea/repos/owner/invalid@repo/commits", headers=admin_headers)
 
         assert response.status_code == 400
         data = response.json()
@@ -60,19 +52,13 @@ class TestGiteaCommits:
 
     def test_list_commits_special_chars_in_owner(self, test_app, admin_headers):
         """Test listing commits with special characters in owner."""
-        response = test_app.get(
-            "/api/gitea/repos/owner$/repo/commits",
-            headers=admin_headers
-        )
+        response = test_app.get("/api/gitea/repos/owner$/repo/commits", headers=admin_headers)
 
         assert response.status_code == 400
 
     def test_list_commits_special_chars_in_repo(self, test_app, admin_headers):
         """Test listing commits with special characters in repo."""
-        response = test_app.get(
-            "/api/gitea/repos/owner/repo!/commits",
-            headers=admin_headers
-        )
+        response = test_app.get("/api/gitea/repos/owner/repo!/commits", headers=admin_headers)
 
         assert response.status_code == 400
 
@@ -81,10 +67,7 @@ class TestGiteaCommits:
         """Test that valid names with allowed characters pass validation."""
         # Valid characters: a-zA-Z0-9._-
         # This will fail at the HTTP call level, but should pass validation
-        response = test_app.get(
-            "/api/gitea/repos/valid-owner_123/repo.name-456/commits",
-            headers=admin_headers
-        )
+        response = test_app.get("/api/gitea/repos/valid-owner_123/repo.name-456/commits", headers=admin_headers)
 
         # Should not be 400 (validation error), but may be 500/503 (HTTP error)
         assert response.status_code != 400
@@ -94,4 +77,3 @@ class TestGiteaCommits:
         response = test_app.get("/api/gitea/repos/owner/repo/commits")
 
         assert response.status_code == 401
-