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/loaders/node-loader.ts

@@ -0,0 +1,87 @@
+import path from 'path';
+
+export interface LoadedNode {
+  packageName: string;
+  nodeName: string;
+  NodeClass: any;
+}
+
+export class N8nNodeLoader {
+  private readonly CORE_PACKAGES = [
+    'n8n-nodes-base',
+    '@n8n/n8n-nodes-langchain'
+  ];
+
+  async loadAllNodes(): Promise<LoadedNode[]> {
+    const results: LoadedNode[] = [];
+    
+    for (const pkg of this.CORE_PACKAGES) {
+      try {
+        console.log(`\n📦 Loading package: ${pkg}`);
+        // Direct require - no complex path resolution
+        const packageJson = require(`${pkg}/package.json`);
+        console.log(`  Found ${Object.keys(packageJson.n8n?.nodes || {}).length} nodes in package.json`);
+        const nodes = await this.loadPackageNodes(pkg, packageJson);
+        results.push(...nodes);
+      } catch (error) {
+        console.error(`Failed to load ${pkg}:`, error);
+      }
+    }
+    
+    return results;
+  }
+
+  private async loadPackageNodes(packageName: string, packageJson: any): Promise<LoadedNode[]> {
+    const n8nConfig = packageJson.n8n || {};
+    const nodes: LoadedNode[] = [];
+    
+    // Check if nodes is an array or object
+    const nodesList = n8nConfig.nodes || [];
+    
+    if (Array.isArray(nodesList)) {
+      // Handle array format (n8n-nodes-base uses this)
+      for (const nodePath of nodesList) {
+        try {
+          const fullPath = require.resolve(`${packageName}/${nodePath}`);
+          const nodeModule = require(fullPath);
+          
+          // Extract node name from path (e.g., "dist/nodes/Slack/Slack.node.js" -> "Slack")
+          const nodeNameMatch = nodePath.match(/\/([^\/]+)\.node\.(js|ts)$/);
+          const nodeName = nodeNameMatch ? nodeNameMatch[1] : path.basename(nodePath, '.node.js');
+          
+          // Handle default export and various export patterns
+          const NodeClass = nodeModule.default || nodeModule[nodeName] || Object.values(nodeModule)[0];
+          if (NodeClass) {
+            nodes.push({ packageName, nodeName, NodeClass });
+            console.log(`  ✓ Loaded ${nodeName} from ${packageName}`);
+          } else {
+            console.warn(`  ⚠ No valid export found for ${nodeName} in ${packageName}`);
+          }
+        } catch (error) {
+          console.error(`  ✗ Failed to load node from ${packageName}/${nodePath}:`, (error as Error).message);
+        }
+      }
+    } else {
+      // Handle object format (for other packages)
+      for (const [nodeName, nodePath] of Object.entries(nodesList)) {
+        try {
+          const fullPath = require.resolve(`${packageName}/${nodePath as string}`);
+          const nodeModule = require(fullPath);
+          
+          // Handle default export and various export patterns
+          const NodeClass = nodeModule.default || nodeModule[nodeName] || Object.values(nodeModule)[0];
+          if (NodeClass) {
+            nodes.push({ packageName, nodeName, NodeClass });
+            console.log(`  ✓ Loaded ${nodeName} from ${packageName}`);
+          } else {
+            console.warn(`  ⚠ No valid export found for ${nodeName} in ${packageName}`);
+          }
+        } catch (error) {
+          console.error(`  ✗ Failed to load node ${nodeName} from ${packageName}:`, (error as Error).message);
+        }
+      }
+    }
+    
+    return nodes;
+  }
+}