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_files.py

@@ -1,7 +1,7 @@
 """
 Integration tests for file operations.
 """
-import pytest
+
 import os
 
 
@@ -10,11 +10,7 @@ class TestFileBrowse:
 
     def test_browse_root(self, test_app, admin_headers, temp_volume_root):
         """Test browsing root directory."""
-        response = test_app.get(
-            "/api/files/browse",
-            headers=admin_headers,
-            params={"path": "/"}
-        )
+        response = test_app.get("/api/files/browse", headers=admin_headers, params={"path": "/"})
 
         assert response.status_code == 200
         data = response.json()
@@ -28,22 +24,14 @@ class TestFileBrowse:
 
     def test_browse_blocked_directory(self, test_app, admin_headers):
         """Test browsing blocked directory."""
-        response = test_app.get(
-            "/api/files/browse",
-            headers=admin_headers,
-            params={"path": "/@appstore"}
-        )
+        response = test_app.get("/api/files/browse", headers=admin_headers, params={"path": "/@appstore"})
 
         # Should be forbidden
         assert response.status_code == 403
 
     def test_browse_path_traversal_attempt(self, test_app, admin_headers):
         """Test path traversal protection."""
-        response = test_app.get(
-            "/api/files/browse",
-            headers=admin_headers,
-            params={"path": "/../../../etc"}
-        )
+        response = test_app.get("/api/files/browse", headers=admin_headers, params={"path": "/../../../etc"})
 
         # Should be forbidden
         assert response.status_code == 403
@@ -57,12 +45,7 @@ class TestFileUpload:
         test_content = b"test file content"
         files = {"file": ("test.txt", test_content, "text/plain")}
 
-        response = test_app.post(
-            "/api/files/upload",
-            headers=admin_headers,
-            files=files,
-            params={"path": "/"}
-        )
+        response = test_app.post("/api/files/upload", headers=admin_headers, files=files, params={"path": "/"})
 
         assert response.status_code in [200, 201]
 
@@ -70,32 +53,23 @@ class TestFileUpload:
         """Test upload without authentication."""
         files = {"file": ("test.txt", b"content", "text/plain")}
 
-        response = test_app.post(
-            "/api/files/upload",
-            files=files,
-            params={"path": "/"}
-        )
+        response = test_app.post("/api/files/upload", files=files, params={"path": "/"})
 
         assert response.status_code == 401
 
     def test_upload_as_member_forbidden(self, test_app, mock_config, temp_auth_file, temp_rbac_file):
         """Test that non-admin cannot upload."""
-        from auth_service import create_access_token
         from datetime import timedelta
 
+        from auth_service import create_access_token
+
         member_token = create_access_token(
-            data={"sub": "memberuser", "role": "member"},
-            expires_delta=timedelta(minutes=30)
+            data={"sub": "memberuser", "role": "member"}, expires_delta=timedelta(minutes=30)
         )
         headers = {"Authorization": f"Bearer {member_token}"}
         files = {"file": ("test.txt", b"content", "text/plain")}
 
-        response = test_app.post(
-            "/api/files/upload",
-            headers=headers,
-            files=files,
-            params={"path": "/"}
-        )
+        response = test_app.post("/api/files/upload", headers=headers, files=files, params={"path": "/"})
 
         # Upload should be admin-only
         assert response.status_code == 403
@@ -111,39 +85,28 @@ class TestFileDelete:
         with open(test_file, "w") as f:
             f.write("test content")
 
-        response = test_app.delete(
-            "/api/files/delete",
-            headers=admin_headers,
-            params={"path": "/test_delete.txt"}
-        )
+        response = test_app.delete("/api/files/delete", headers=admin_headers, params={"path": "/test_delete.txt"})
 
         assert response.status_code in [200, 204]
 
     def test_delete_without_auth(self, test_app):
         """Test delete without authentication."""
-        response = test_app.delete(
-            "/api/files/delete",
-            params={"path": "/test.txt"}
-        )
+        response = test_app.delete("/api/files/delete", params={"path": "/test.txt"})
 
         assert response.status_code == 401
 
     def test_delete_as_member_forbidden(self, test_app, mock_config, temp_auth_file, temp_rbac_file):
         """Test that non-admin cannot delete."""
-        from auth_service import create_access_token
         from datetime import timedelta
 
+        from auth_service import create_access_token
+
         member_token = create_access_token(
-            data={"sub": "memberuser", "role": "member"},
-            expires_delta=timedelta(minutes=30)
+            data={"sub": "memberuser", "role": "member"}, expires_delta=timedelta(minutes=30)
         )
         headers = {"Authorization": f"Bearer {member_token}"}
 
-        response = test_app.delete(
-            "/api/files/delete",
-            headers=headers,
-            params={"path": "/test.txt"}
-        )
+        response = test_app.delete("/api/files/delete", headers=headers, params={"path": "/test.txt"})
 
         # Delete should be admin-only
         assert response.status_code == 403
@@ -160,30 +123,19 @@ class TestFileDownload:
         with open(test_file, "w") as f:
             f.write(test_content)
 
-        response = test_app.get(
-            "/api/files/download",
-            headers=admin_headers,
-            params={"path": "/test_download.txt"}
-        )
+        response = test_app.get("/api/files/download", headers=admin_headers, params={"path": "/test_download.txt"})
 
         assert response.status_code == 200
         assert test_content in response.text or response.content == test_content.encode()
 
     def test_download_without_auth(self, test_app):
         """Test download without authentication."""
-        response = test_app.get(
-            "/api/files/download",
-            params={"path": "/test.txt"}
-        )
+        response = test_app.get("/api/files/download", params={"path": "/test.txt"})
 
         assert response.status_code == 401
 
     def test_download_nonexistent_file(self, test_app, admin_headers):
         """Test downloading nonexistent file."""
-        response = test_app.get(
-            "/api/files/download",
-            headers=admin_headers,
-            params={"path": "/nonexistent.txt"}
-        )
+        response = test_app.get("/api/files/download", headers=admin_headers, params={"path": "/nonexistent.txt"})
 
         assert response.status_code == 404