feat: rename n8n_trigger_webhook_workflow to n8n_test_workflow with multi-trigger support (#460)

* feat: rename n8n_trigger_webhook_workflow to n8n_test_workflow with multi-trigger support

- Rename tool from n8n_trigger_webhook_workflow to n8n_test_workflow
- Add support for webhook, form, and chat triggers (auto-detection)
- Implement modular trigger system with registry pattern
- Add trigger detector for automatic trigger type inference
- Remove execute trigger type (n8n public API limitation)
- Add comprehensive tests for trigger detection and handlers

The tool now auto-detects trigger type from workflow structure and
supports all externally-triggerable workflows via n8n's public API.

Note: Direct workflow execution (Schedule/Manual triggers) requires
n8n's instance-level MCP access, not available via REST API.

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

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

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

* fix: add SSRF protection to webhook handler and update tests

- Add SSRF URL validation to webhook-handler.ts (critical security fix)
  Aligns with existing SSRF protection in form-handler.ts and chat-handler.ts
- Update parameter-validation.test.ts to use new n8n_test_workflow tool name

Conceived by Romuald Członkowski - www.aiadvisors.pl/en

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

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

* feat: n8n_test_workflow unified trigger tool (v2.28.0)

Added new `n8n_test_workflow` tool replacing `n8n_trigger_webhook_workflow`:

Features:
- Auto-detects trigger type (webhook/form/chat) from workflow
- Supports multiple trigger types with type-specific parameters
- SSRF protection for all trigger handlers
- Extensible handler architecture with registry pattern

Changes:
- Fixed Zod schema to remove invalid 'execute' trigger type
- Updated README.md tool documentation
- Added CHANGELOG entry for v2.28.0
- Bumped version to 2.28.0

Conceived by Romuald Członkowski - www.aiadvisors.pl/en

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

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

* test: add comprehensive unit tests for trigger handlers

Added 87 unit tests across 4 test files to improve code coverage:

- base-handler.test.ts (19 tests) - 100% coverage
- webhook-handler.test.ts (22 tests) - 100% coverage
- chat-handler.test.ts (23 tests) - 100% coverage
- form-handler.test.ts (23 tests) - 100% coverage

Tests cover:
- Input validation and parameter handling
- SSRF protection integration
- HTTP method handling and URL building
- Error response formatting
- Execution paths for all trigger types

Conceived by Romuald Członkowski - www.aiadvisors.pl/en

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

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

tests/unit/triggers/trigger-registry.test.ts

@@ -0,0 +1,156 @@
+/**
+ * Unit tests for trigger registry
+ */
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { TriggerRegistry, initializeTriggerRegistry, ensureRegistryInitialized } from '../../../src/triggers/trigger-registry';
+import type { N8nApiClient } from '../../../src/services/n8n-api-client';
+
+// Mock N8nApiClient
+const createMockClient = (): N8nApiClient => ({
+  getWorkflow: vi.fn(),
+  listWorkflows: vi.fn(),
+  createWorkflow: vi.fn(),
+  updateWorkflow: vi.fn(),
+  deleteWorkflow: vi.fn(),
+  triggerWebhook: vi.fn(),
+  getExecution: vi.fn(),
+  listExecutions: vi.fn(),
+  deleteExecution: vi.fn(),
+} as unknown as N8nApiClient);
+
+describe('TriggerRegistry', () => {
+  describe('initialization', () => {
+    it('should initialize with all handlers registered', async () => {
+      await initializeTriggerRegistry();
+
+      const registeredTypes = TriggerRegistry.getRegisteredTypes();
+
+      expect(registeredTypes).toContain('webhook');
+      expect(registeredTypes).toContain('form');
+      expect(registeredTypes).toContain('chat');
+      expect(registeredTypes.length).toBe(3);
+    });
+
+    it('should not register duplicate handlers on multiple init calls', async () => {
+      await initializeTriggerRegistry();
+      const firstTypes = TriggerRegistry.getRegisteredTypes();
+
+      await initializeTriggerRegistry();
+      const secondTypes = TriggerRegistry.getRegisteredTypes();
+
+      expect(firstTypes.length).toBe(secondTypes.length);
+    });
+  });
+
+  describe('hasHandler', () => {
+    beforeEach(async () => {
+      await ensureRegistryInitialized();
+    });
+
+    it('should return true for webhook handler', () => {
+      expect(TriggerRegistry.hasHandler('webhook')).toBe(true);
+    });
+
+    it('should return true for form handler', () => {
+      expect(TriggerRegistry.hasHandler('form')).toBe(true);
+    });
+
+    it('should return true for chat handler', () => {
+      expect(TriggerRegistry.hasHandler('chat')).toBe(true);
+    });
+
+    it('should return false for unknown trigger type', () => {
+      expect(TriggerRegistry.hasHandler('unknown' as any)).toBe(false);
+    });
+  });
+
+  describe('getHandler', () => {
+    let mockClient: N8nApiClient;
+
+    beforeEach(async () => {
+      await ensureRegistryInitialized();
+      mockClient = createMockClient();
+    });
+
+    it('should return a webhook handler', () => {
+      const handler = TriggerRegistry.getHandler('webhook', mockClient);
+
+      expect(handler).toBeDefined();
+      expect(handler?.triggerType).toBe('webhook');
+    });
+
+    it('should return a form handler', () => {
+      const handler = TriggerRegistry.getHandler('form', mockClient);
+
+      expect(handler).toBeDefined();
+      expect(handler?.triggerType).toBe('form');
+    });
+
+    it('should return a chat handler', () => {
+      const handler = TriggerRegistry.getHandler('chat', mockClient);
+
+      expect(handler).toBeDefined();
+      expect(handler?.triggerType).toBe('chat');
+    });
+
+    it('should return undefined for unknown trigger type', () => {
+      const handler = TriggerRegistry.getHandler('unknown' as any, mockClient);
+
+      expect(handler).toBeUndefined();
+    });
+  });
+
+  describe('handler capabilities', () => {
+    let mockClient: N8nApiClient;
+
+    beforeEach(async () => {
+      await ensureRegistryInitialized();
+      mockClient = createMockClient();
+    });
+
+    it('webhook handler should require active workflow', () => {
+      const handler = TriggerRegistry.getHandler('webhook', mockClient);
+
+      expect(handler?.capabilities.requiresActiveWorkflow).toBe(true);
+      expect(handler?.capabilities.canPassInputData).toBe(true);
+    });
+
+    it('form handler should require active workflow', () => {
+      const handler = TriggerRegistry.getHandler('form', mockClient);
+
+      expect(handler?.capabilities.requiresActiveWorkflow).toBe(true);
+      expect(handler?.capabilities.canPassInputData).toBe(true);
+    });
+
+    it('chat handler should require active workflow', () => {
+      const handler = TriggerRegistry.getHandler('chat', mockClient);
+
+      expect(handler?.capabilities.requiresActiveWorkflow).toBe(true);
+      expect(handler?.capabilities.canPassInputData).toBe(true);
+    });
+  });
+
+  describe('ensureRegistryInitialized', () => {
+    it('should be safe to call multiple times', async () => {
+      await ensureRegistryInitialized();
+      await ensureRegistryInitialized();
+      await ensureRegistryInitialized();
+
+      const types = TriggerRegistry.getRegisteredTypes();
+      expect(types.length).toBe(3);
+    });
+
+    it('should handle concurrent initialization calls', async () => {
+      const promises = [
+        ensureRegistryInitialized(),
+        ensureRegistryInitialized(),
+        ensureRegistryInitialized(),
+      ];
+
+      await Promise.all(promises);
+
+      const types = TriggerRegistry.getRegisteredTypes();
+      expect(types.length).toBe(3);
+    });
+  });
+});