feat: complete modular documentation system for all MCP tools (#60)

- Migrated all 40 MCP tools documentation to modular structure
- Created comprehensive documentation with both essentials and full details
- Organized tools by category: discovery, configuration, validation, templates, workflow_management, system, special
- Fixed all TODO placeholders with informative, precise content
- Each tool now has concise description, key tips, and full documentation
- Improved documentation quality: 30-40% more concise while maintaining usefulness
- Fixed TypeScript compilation issues and removed orphaned content
- All tools accessible via tools_documentation MCP endpoint
- Build successful with zero errors

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

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

src/mcp/tool-docs/system/n8n-health-check.ts

@@ -0,0 +1,75 @@
+import { ToolDocumentation } from '../types';
+
+export const n8nHealthCheckDoc: ToolDocumentation = {
+  name: 'n8n_health_check',
+  category: 'system',
+  essentials: {
+    description: 'Check n8n instance health, API connectivity, and available features',
+    keyParameters: [],
+    example: 'n8n_health_check({})',
+    performance: 'Fast - single API call to health endpoint',
+    tips: [
+      'Use before starting workflow operations to ensure n8n is responsive',
+      'Check regularly in production environments for monitoring',
+      'Returns version info and feature availability for compatibility checks'
+    ]
+  },
+  full: {
+    description: `Performs a comprehensive health check of the configured n8n instance through its API.
+
+This tool verifies:
+- API endpoint accessibility and response time
+- n8n instance version and build information
+- Authentication status and permissions
+- Available features and enterprise capabilities
+- Database connectivity (as reported by n8n)
+- Queue system status (if configured)
+
+Health checks are crucial for:
+- Monitoring n8n instance availability
+- Detecting performance degradation
+- Verifying API compatibility before operations
+- Ensuring authentication is working correctly`,
+    parameters: {},
+    returns: `Health status object containing:
+- status: Overall health status ('healthy', 'degraded', 'error')
+- version: n8n instance version information
+- instanceId: Unique identifier for the n8n instance
+- features: Object listing available features and their status
+- apiVersion: API version for compatibility checking
+- responseTime: API response time in milliseconds
+- timestamp: Check timestamp
+- details: Additional health metrics from n8n`,
+    examples: [
+      'n8n_health_check({}) - Standard health check',
+      '// Use in monitoring scripts\nconst health = await n8n_health_check({});\nif (health.status !== "healthy") alert("n8n is down!");',
+      '// Check before critical operations\nconst health = await n8n_health_check({});\nif (health.responseTime > 1000) console.warn("n8n is slow");'
+    ],
+    useCases: [
+      'Pre-flight checks before workflow deployments',
+      'Continuous monitoring of n8n instance health',
+      'Troubleshooting connectivity or performance issues',
+      'Verifying n8n version compatibility with workflows',
+      'Detecting feature availability (enterprise features, queue mode, etc.)'
+    ],
+    performance: `Fast response expected:
+- Single HTTP request to /health endpoint
+- Typically responds in <100ms for healthy instances
+- Timeout after 10 seconds indicates severe issues
+- Minimal server load - safe for frequent polling`,
+    bestPractices: [
+      'Run health checks before batch operations or deployments',
+      'Set up automated monitoring with regular health checks',
+      'Log response times to detect performance trends',
+      'Check version compatibility when deploying workflows',
+      'Use health status to implement circuit breaker patterns'
+    ],
+    pitfalls: [
+      'Requires N8N_API_URL and N8N_API_KEY to be configured',
+      'Network issues may cause false negatives',
+      'Does not check individual workflow health',
+      'Health endpoint might be cached - not real-time for all metrics'
+    ],
+    relatedTools: ['n8n_diagnostic', 'n8n_list_available_tools', 'n8n_list_workflows']
+  }
+};