feat: implement anonymous telemetry system with Supabase integration

Adds zero-configuration anonymous usage statistics to track:
- Number of active users with deterministic user IDs
- Which MCP tools AI agents use most
- What workflows are built (sanitized to protect privacy)
- Common errors and issues

Key features:
- Zero-configuration design with hardcoded write-only credentials
- Privacy-first approach with comprehensive data sanitization
- Opt-out support via config file and environment variables
- Docker-friendly with environment variable support
- Multi-process safe with immediate flush strategy
- Row Level Security (RLS) policies for write-only access

Technical implementation:
- Supabase backend with anon key for INSERT-only operations
- Workflow sanitization removes all sensitive data
- Environment variables checked for opt-out (TELEMETRY_DISABLED, etc.)
- Telemetry enabled by default but respects user preferences
- Cleaned up all debug logging for production readiness

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

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

scripts/test-workflow-tracking-debug.ts

@@ -0,0 +1,71 @@
+#!/usr/bin/env npx tsx
+/**
+ * Debug workflow tracking in telemetry manager
+ */
+
+import { TelemetryManager } from '../src/telemetry/telemetry-manager';
+
+// Get the singleton instance
+const telemetry = TelemetryManager.getInstance();
+
+const testWorkflow = {
+  nodes: [
+    {
+      id: 'webhook1',
+      type: 'n8n-nodes-base.webhook',
+      name: 'Webhook',
+      position: [0, 0],
+      parameters: { 
+        path: '/test-' + Date.now(),
+        httpMethod: 'POST'
+      }
+    },
+    {
+      id: 'http1',
+      type: 'n8n-nodes-base.httpRequest',
+      name: 'HTTP Request',
+      position: [250, 0],
+      parameters: { 
+        url: 'https://api.example.com/data',
+        method: 'GET'
+      }
+    },
+    {
+      id: 'slack1',
+      type: 'n8n-nodes-base.slack',
+      name: 'Slack',
+      position: [500, 0],
+      parameters: {
+        channel: '#general',
+        text: 'Workflow complete!'
+      }
+    }
+  ],
+  connections: {
+    'webhook1': {
+      main: [[{ node: 'http1', type: 'main', index: 0 }]]
+    },
+    'http1': {
+      main: [[{ node: 'slack1', type: 'main', index: 0 }]]
+    }
+  }
+};
+
+console.log('🧪 Testing Workflow Tracking\n');
+console.log('Workflow has', testWorkflow.nodes.length, 'nodes');
+
+// Track the workflow
+console.log('Calling trackWorkflowCreation...');
+telemetry.trackWorkflowCreation(testWorkflow, true);
+
+console.log('Waiting for async processing...');
+
+// Wait for setImmediate to process
+setTimeout(async () => {
+  console.log('\nForcing flush...');
+  await telemetry.flush();
+  console.log('✅ Flush complete!');
+  
+  console.log('\nWorkflow should now be in the telemetry_workflows table.');
+  console.log('Check with: SELECT * FROM telemetry_workflows ORDER BY created_at DESC LIMIT 1;');
+}, 2000);