feat: implement 5 QA-driven security and quality proposals

Implemented proposals from comprehensive QA review:

1. extend-csrf-protection
   - Add POST to CSRF protected methods in frontend
   - Global CSRF middleware for all state-changing operations
   - Update tests with CSRF token fixtures

2. tighten-cors-websocket-security
   - Replace wildcard CORS with explicit method/header lists
   - Disable query parameter auth in production (code 4002)
   - Add per-user WebSocket connection limit (max 5, code 4005)

3. shorten-jwt-expiry
   - Reduce JWT expiry from 7 days to 60 minutes
   - Add refresh token support with 7-day expiry
   - Implement token rotation on refresh
   - Frontend auto-refresh when token near expiry (<5 min)

4. fix-frontend-quality
   - Add React.lazy() code splitting for all pages
   - Fix useCallback dependency arrays (Dashboard, Comments)
   - Add localStorage data validation in AuthContext
   - Complete i18n for AttachmentUpload component

5. enhance-backend-validation
   - Add SecurityAuditMiddleware for access denied logging
   - Add ErrorSanitizerMiddleware for production error messages
   - Protect /health/detailed with admin authentication
   - Add input length validation (comment 5000, desc 10000)

All 521 backend tests passing. Frontend builds successfully.

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

backend/tests/test_task_dependencies.py

@@ -783,7 +783,7 @@ class TestDateValidation:
 class TestDependencyCRUDAPI:
     """Test dependency CRUD API endpoints."""
 
-    def test_create_dependency(self, client, db, admin_token):
+    def test_create_dependency(self, client, db, admin_token, csrf_token):
         """Test creating a dependency via API."""
         # Create test data
         space = Space(
@@ -838,7 +838,7 @@ class TestDependencyCRUDAPI:
                 "dependency_type": "FS",
                 "lag_days": 0
             },
-            headers={"Authorization": f"Bearer {admin_token}"},
+            headers={"Authorization": f"Bearer {admin_token}", "X-CSRF-Token": csrf_token},
         )
 
         assert response.status_code == 201
@@ -914,7 +914,7 @@ class TestDependencyCRUDAPI:
         assert data["total"] >= 1
         assert any(d["predecessor_id"] == "task-api-list-1" for d in data["dependencies"])
 
-    def test_delete_dependency(self, client, db, admin_token):
+    def test_delete_dependency(self, client, db, admin_token, csrf_token):
         """Test deleting a dependency."""
         # Create test data
         space = Space(
@@ -973,7 +973,7 @@ class TestDependencyCRUDAPI:
         # Delete dependency
         response = client.delete(
             "/api/task-dependencies/dep-api-del",
-            headers={"Authorization": f"Bearer {admin_token}"},
+            headers={"Authorization": f"Bearer {admin_token}", "X-CSRF-Token": csrf_token},
         )
 
         assert response.status_code == 204
@@ -984,7 +984,7 @@ class TestDependencyCRUDAPI:
         ).first()
         assert dep_check is None
 
-    def test_circular_dependency_rejected_via_api(self, client, db, admin_token):
+    def test_circular_dependency_rejected_via_api(self, client, db, admin_token, csrf_token):
         """Test that circular dependencies are rejected via API."""
         # Create test data
         space = Space(
@@ -1049,7 +1049,7 @@ class TestDependencyCRUDAPI:
                 "dependency_type": "FS",
                 "lag_days": 0
             },
-            headers={"Authorization": f"Bearer {admin_token}"},
+            headers={"Authorization": f"Bearer {admin_token}", "X-CSRF-Token": csrf_token},
         )
 
         assert response.status_code == 400
@@ -1060,7 +1060,7 @@ class TestDependencyCRUDAPI:
 class TestTaskDateValidationAPI:
     """Test task date validation in task API."""
 
-    def test_create_task_with_invalid_dates_rejected(self, client, db, admin_token):
+    def test_create_task_with_invalid_dates_rejected(self, client, db, admin_token, csrf_token):
         """Test that creating a task with start_date > due_date is rejected."""
         # Create test data
         space = Space(
@@ -1099,13 +1099,13 @@ class TestTaskDateValidationAPI:
                 "start_date": (now + timedelta(days=10)).isoformat(),
                 "due_date": now.isoformat(),
             },
-            headers={"Authorization": f"Bearer {admin_token}"},
+            headers={"Authorization": f"Bearer {admin_token}", "X-CSRF-Token": csrf_token},
         )
 
         assert response.status_code == 400
         assert "Start date cannot be after due date" in response.json()["detail"]
 
-    def test_update_task_with_invalid_dates_rejected(self, client, db, admin_token):
+    def test_update_task_with_invalid_dates_rejected(self, client, db, admin_token, csrf_token):
         """Test that updating a task to have start_date > due_date is rejected."""
         # Create test data
         space = Space(
@@ -1153,12 +1153,12 @@ class TestTaskDateValidationAPI:
             json={
                 "start_date": (now + timedelta(days=20)).isoformat(),
             },
-            headers={"Authorization": f"Bearer {admin_token}"},
+            headers={"Authorization": f"Bearer {admin_token}", "X-CSRF-Token": csrf_token},
         )
 
         assert response.status_code == 400
 
-    def test_create_task_with_valid_dates_accepted(self, client, db, admin_token):
+    def test_create_task_with_valid_dates_accepted(self, client, db, admin_token, csrf_token):
         """Test that creating a task with valid dates is accepted."""
         # Create test data
         space = Space(
@@ -1197,7 +1197,7 @@ class TestTaskDateValidationAPI:
                 "start_date": now.isoformat(),
                 "due_date": (now + timedelta(days=10)).isoformat(),
             },
-            headers={"Authorization": f"Bearer {admin_token}"},
+            headers={"Authorization": f"Bearer {admin_token}", "X-CSRF-Token": csrf_token},
         )
 
         assert response.status_code == 201
@@ -1217,7 +1217,7 @@ class TestDependencyTypes:
         assert DependencyType.FF.value == "FF"
         assert DependencyType.SF.value == "SF"
 
-    def test_create_dependency_with_different_types(self, client, db, admin_token):
+    def test_create_dependency_with_different_types(self, client, db, admin_token, csrf_token):
         """Test creating dependencies with different types via API."""
         # Create test data
         space = Space(
@@ -1268,7 +1268,7 @@ class TestDependencyTypes:
                     "dependency_type": dep_type,
                     "lag_days": i
                 },
-                headers={"Authorization": f"Bearer {admin_token}"},
+                headers={"Authorization": f"Bearer {admin_token}", "X-CSRF-Token": csrf_token},
             )
 
             assert response.status_code == 201