Restructure marketplace for isolated plugin architecture

- Organize 62 plugins into isolated directories under plugins/
- Consolidate tools and workflows into commands/ following Anthropic conventions
- Update marketplace.json with isolated source paths for each plugin
- Revise README to reflect plugin-based structure and token efficiency
- Remove shared resource directories (agents/, tools/, workflows/)

Each plugin now contains only its specific agents and commands, enabling
granular installation and minimal token usage. Installing a single plugin
loads only its resources rather than the entire marketplace.

Structure: plugins/{plugin-name}/{agents/,commands/}

plugins/tdd-workflows/commands/tdd-red.md

@@ -0,0 +1,135 @@
+Write comprehensive failing tests following TDD red phase principles.
+
+[Extended thinking: Generates failing tests that properly define expected behavior using test-automator agent.]
+
+## Role
+
+Generate failing tests using Task tool with subagent_type="test-automator".
+
+## Prompt Template
+
+"Generate comprehensive FAILING tests for: $ARGUMENTS
+
+## Core Requirements
+
+1. **Test Structure**
+   - Framework-appropriate setup (Jest/pytest/JUnit/Go/RSpec)
+   - Arrange-Act-Assert pattern
+   - should_X_when_Y naming convention
+   - Isolated fixtures with no interdependencies
+
+2. **Behavior Coverage**
+   - Happy path scenarios
+   - Edge cases (empty, null, boundary values)
+   - Error handling and exceptions
+   - Concurrent access (if applicable)
+
+3. **Failure Verification**
+   - Tests MUST fail when run
+   - Failures for RIGHT reasons (not syntax/import errors)
+   - Meaningful diagnostic error messages
+   - No cascading failures
+
+4. **Test Categories**
+   - Unit: Isolated component behavior
+   - Integration: Component interaction
+   - Contract: API/interface contracts
+   - Property: Mathematical invariants
+
+## Framework Patterns
+
+**JavaScript/TypeScript (Jest/Vitest)**
+- Mock dependencies with `vi.fn()` or `jest.fn()`
+- Use `@testing-library` for React components
+- Property tests with `fast-check`
+
+**Python (pytest)**
+- Fixtures with appropriate scopes
+- Parametrize for multiple test cases
+- Hypothesis for property-based tests
+
+**Go**
+- Table-driven tests with subtests
+- `t.Parallel()` for parallel execution
+- Use `testify/assert` for cleaner assertions
+
+**Ruby (RSpec)**
+- `let` for lazy loading, `let!` for eager
+- Contexts for different scenarios
+- Shared examples for common behavior
+
+## Quality Checklist
+
+- Readable test names documenting intent
+- One behavior per test
+- No implementation leakage
+- Meaningful test data (not 'foo'/'bar')
+- Tests serve as living documentation
+
+## Anti-Patterns to Avoid
+
+- Tests passing immediately
+- Testing implementation vs behavior
+- Complex setup code
+- Multiple responsibilities per test
+- Brittle tests tied to specifics
+
+## Edge Case Categories
+
+- **Null/Empty**: undefined, null, empty string/array/object
+- **Boundaries**: min/max values, single element, capacity limits
+- **Special Cases**: Unicode, whitespace, special characters
+- **State**: Invalid transitions, concurrent modifications
+- **Errors**: Network failures, timeouts, permissions
+
+## Output Requirements
+
+- Complete test files with imports
+- Documentation of test purpose
+- Commands to run and verify failures
+- Metrics: test count, coverage areas
+- Next steps for green phase"
+
+## Validation
+
+After generation:
+1. Run tests - confirm they fail
+2. Verify helpful failure messages
+3. Check test independence
+4. Ensure comprehensive coverage
+
+## Example (Minimal)
+
+```typescript
+// auth.service.test.ts
+describe('AuthService', () => {
+  let authService: AuthService;
+  let mockUserRepo: jest.Mocked<UserRepository>;
+
+  beforeEach(() => {
+    mockUserRepo = { findByEmail: jest.fn() } as any;
+    authService = new AuthService(mockUserRepo);
+  });
+
+  it('should_return_token_when_valid_credentials', async () => {
+    const user = { id: '1', email: 'test@example.com', passwordHash: 'hashed' };
+    mockUserRepo.findByEmail.mockResolvedValue(user);
+
+    const result = await authService.authenticate('test@example.com', 'pass');
+
+    expect(result.success).toBe(true);
+    expect(result.token).toBeDefined();
+  });
+
+  it('should_fail_when_user_not_found', async () => {
+    mockUserRepo.findByEmail.mockResolvedValue(null);
+
+    const result = await authService.authenticate('none@example.com', 'pass');
+
+    expect(result.success).toBe(false);
+    expect(result.error).toBe('INVALID_CREDENTIALS');
+  });
+});
+```
+
+Test requirements: $ARGUMENTS