feat: Implement n8n-MCP Enhancement Plan v2.1 Final

- Implement simple node loader supporting n8n-nodes-base and langchain packages
- Create parser handling declarative, programmatic, and versioned nodes
- Build documentation mapper with 89% coverage (405/457 nodes)
- Setup SQLite database with minimal schema
- Create rebuild script for one-command database updates
- Implement validation script for critical nodes
- Update MCP server with documentation-focused tools
- Add npm scripts for streamlined workflow

Successfully loads 457/458 nodes with accurate documentation mapping.
Versioned node detection working (46 nodes detected).
3/4 critical nodes pass validation tests.

Known limitations:
- Slack operations extraction incomplete for some versioned nodes
- One langchain node fails due to missing dependency
- No AI tools detected (none have usableAsTool flag)

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

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

src/mappers/docs-mapper.ts

@@ -0,0 +1,63 @@
+import { promises as fs } from 'fs';
+import path from 'path';
+
+export class DocsMapper {
+  private docsPath = path.join(process.cwd(), 'n8n-docs');
+  
+  // Known documentation mapping fixes
+  private readonly KNOWN_FIXES: Record<string, string> = {
+    'httpRequest': 'httprequest',
+    'code': 'code',
+    'webhook': 'webhook',
+    'respondToWebhook': 'respondtowebhook',
+    // With package prefix
+    'n8n-nodes-base.httpRequest': 'httprequest',
+    'n8n-nodes-base.code': 'code',
+    'n8n-nodes-base.webhook': 'webhook',
+    'n8n-nodes-base.respondToWebhook': 'respondtowebhook'
+  };
+
+  async fetchDocumentation(nodeType: string): Promise<string | null> {
+    // Apply known fixes first
+    const fixedType = this.KNOWN_FIXES[nodeType] || nodeType;
+    
+    // Extract node name
+    const nodeName = fixedType.split('.').pop()?.toLowerCase();
+    if (!nodeName) {
+      console.log(`⚠️  Could not extract node name from: ${nodeType}`);
+      return null;
+    }
+    
+    console.log(`📄 Looking for docs for: ${nodeType} -> ${nodeName}`);
+    
+    // Try different documentation paths - both files and directories
+    const possiblePaths = [
+      // Direct file paths
+      `docs/integrations/builtin/core-nodes/n8n-nodes-base.${nodeName}.md`,
+      `docs/integrations/builtin/app-nodes/n8n-nodes-base.${nodeName}.md`,
+      `docs/integrations/builtin/trigger-nodes/n8n-nodes-base.${nodeName}.md`,
+      `docs/integrations/builtin/cluster-nodes/sub-nodes/n8n-nodes-langchain.${nodeName}.md`,
+      // Directory with index.md
+      `docs/integrations/builtin/core-nodes/n8n-nodes-base.${nodeName}/index.md`,
+      `docs/integrations/builtin/app-nodes/n8n-nodes-base.${nodeName}/index.md`,
+      `docs/integrations/builtin/trigger-nodes/n8n-nodes-base.${nodeName}/index.md`,
+      `docs/integrations/builtin/cluster-nodes/sub-nodes/n8n-nodes-langchain.${nodeName}/index.md`
+    ];
+    
+    // Try each path
+    for (const relativePath of possiblePaths) {
+      try {
+        const fullPath = path.join(this.docsPath, relativePath);
+        const content = await fs.readFile(fullPath, 'utf-8');
+        console.log(`  ✓ Found docs at: ${relativePath}`);
+        return content;
+      } catch (error) {
+        // File doesn't exist, try next
+        continue;
+      }
+    }
+    
+    console.log(`  ✗ No docs found for ${nodeName}`);
+    return null;
+  }
+}