Clean up legacy code after unified architecture implementation

- Remove obsolete cmd/auto_enhance.go command (replaced by unified enhance)
- Implement EnhanceInPlace method using unified pipeline
- Remove generated demo files from git tracking
- Verify all functionality works after cleanup:
  * go build successful
  * enhance command working correctly
  * unified pipeline (discovery → ID generation → content injection) verified
  * clean command structure (only enhance, serve, restore commands)

The codebase is now clean with no legacy auto-enhance references or stub implementations. All functionality consolidated into the unified Discoverer + Enhancer architecture.

test-sites/demo-site/insertr.yaml

@@ -0,0 +1,27 @@
+# Insertr Configuration for Default Demo Site
+# Main configuration for the default demo site
+
+# Global settings
+dev_mode: true           # Development mode for demos
+
+# Database configuration  
+database:
+  path: "./insertr.db"   # Shared database with main config
+
+# Demo-specific configuration
+demo:
+  site_id: "demo"        # Unique site ID for default demo
+  inject_demo_gate: true # Auto-inject demo gate if no gates exist
+  mock_auth: true        # Use mock authentication for demos
+  api_endpoint: "http://localhost:8080/api/content"
+  demo_port: 3000        # Port for live-server
+
+# CLI enhancement configuration
+cli:
+  site_id: "demo"        # Site ID for this demo
+  output: "./demo_enhanced" # Output directory for enhanced files
+  inject_demo_gate: true # Inject demo gate in development mode
+
+# Authentication configuration (for demo)
+auth:
+  provider: "mock"       # Mock auth for demos