refactor: Extract reusable UI components and add TDD documentation

- Add comprehensive TDD documentation to CLAUDE.md with coverage requirements and examples
- Extract reusable UI components to frontend/src/components/ui/ (Modal, FormInput, Button, Alert, etc.)
- Add shared constants (schedulePresets) and utility hooks (useCrudMutation, useFormValidation)
- Update frontend/CLAUDE.md with component documentation and usage examples
- Refactor CreateTaskModal to use shared components and constants
- Fix test assertions to be more robust and accurate across all test files

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

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

CLAUDE.md

@@ -21,6 +21,169 @@
 
 Note: `lvh.me` resolves to `127.0.0.1` - required for subdomain cookies to work.
 
+## CRITICAL: Test-Driven Development (TDD) Required
+
+**All code changes MUST follow TDD.** This is non-negotiable.
+
+### TDD Workflow
+
+1. **Write tests FIRST** before writing any implementation code
+2. **Run tests** to verify they fail (red)
+3. **Write minimal code** to make tests pass (green)
+4. **Refactor** while keeping tests green
+5. **Repeat** for each new feature or bug fix
+
+### Coverage Requirements
+
+| Target | Minimum | Goal |
+|--------|---------|------|
+| Backend (Django) | **80%** | 100% |
+| Frontend (React) | **80%** | 100% |
+
+### Running Tests with Coverage
+
+**Backend (Django):**
+```bash
+cd /home/poduck/Desktop/smoothschedule2/smoothschedule
+
+# Run all tests with coverage
+docker compose -f docker-compose.local.yml exec django pytest --cov --cov-report=term-missing
+
+# Run tests for a specific app
+docker compose -f docker-compose.local.yml exec django pytest smoothschedule/scheduling/schedule/tests/ --cov=smoothschedule/scheduling/schedule
+
+# Run a single test file
+docker compose -f docker-compose.local.yml exec django pytest smoothschedule/path/to/test_file.py -v
+
+# Run tests matching a pattern
+docker compose -f docker-compose.local.yml exec django pytest -k "test_create_resource" -v
+```
+
+**Frontend (React):**
+```bash
+cd /home/poduck/Desktop/smoothschedule2/frontend
+
+# Run all tests with coverage
+npm test -- --coverage
+
+# Run tests in watch mode during development
+npm test
+
+# Run a single test file
+npm test -- src/hooks/__tests__/useResources.test.ts
+
+# Run tests matching a pattern
+npm test -- -t "should create resource"
+```
+
+### Test File Organization
+
+**Backend:**
+```
+smoothschedule/smoothschedule/{domain}/{app}/
+├── models.py
+├── views.py
+├── serializers.py
+└── tests/
+    ├── __init__.py
+    ├── test_models.py      # Model unit tests
+    ├── test_serializers.py # Serializer tests
+    ├── test_views.py       # API endpoint tests
+    └── factories.py        # Test factories (optional)
+```
+
+**Frontend:**
+```
+frontend/src/
+├── hooks/
+│   ├── useResources.ts
+│   └── __tests__/
+│       └── useResources.test.ts
+├── components/
+│   ├── MyComponent.tsx
+│   └── __tests__/
+│       └── MyComponent.test.tsx
+└── pages/
+    ├── MyPage.tsx
+    └── __tests__/
+        └── MyPage.test.tsx
+```
+
+### What to Test
+
+**Backend:**
+- Model methods and properties
+- Model validation (clean methods)
+- Serializer validation
+- API endpoints (all HTTP methods)
+- Permission classes
+- Custom querysets and managers
+- Signals
+- Celery tasks
+- Utility functions
+
+**Frontend:**
+- Custom hooks (state changes, API calls)
+- Component rendering
+- User interactions (clicks, form submissions)
+- Conditional rendering
+- Error states
+- Loading states
+- API client functions
+
+### TDD Example - Adding a New Feature
+
+**Step 1: Write the test first**
+```python
+# Backend: test_views.py
+def test_create_resource_with_schedule(self, api_client, tenant):
+    """New feature: resources can have a default schedule."""
+    data = {
+        "name": "Test Resource",
+        "type": "STAFF",
+        "default_schedule": {
+            "monday": {"start": "09:00", "end": "17:00"},
+            "tuesday": {"start": "09:00", "end": "17:00"},
+        }
+    }
+    response = api_client.post("/api/resources/", data, format="json")
+    assert response.status_code == 201
+    assert response.data["default_schedule"]["monday"]["start"] == "09:00"
+```
+
+```typescript
+// Frontend: useResources.test.ts
+it('should create resource with schedule', async () => {
+  const { result } = renderHook(() => useCreateResource());
+
+  await act(async () => {
+    await result.current.mutateAsync({
+      name: 'Test Resource',
+      type: 'STAFF',
+      defaultSchedule: { monday: { start: '09:00', end: '17:00' } }
+    });
+  });
+
+  expect(mockApiClient.post).toHaveBeenCalledWith('/resources/', expect.objectContaining({
+    default_schedule: expect.any(Object)
+  }));
+});
+```
+
+**Step 2: Run tests - they should FAIL**
+
+**Step 3: Write minimal implementation to make tests pass**
+
+**Step 4: Refactor if needed while keeping tests green**
+
+### Pre-Commit Checklist
+
+Before committing ANY code:
+1. [ ] Tests written BEFORE implementation
+2. [ ] All tests pass
+3. [ ] Coverage meets minimum threshold (80%)
+4. [ ] No skipped or disabled tests without justification
+
 ## CRITICAL: Backend Runs in Docker
 
 **NEVER run Django commands directly.** Always use Docker Compose: