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.

insertr.yaml

@@ -13,13 +13,18 @@ server:
   port: 8080            # HTTP API server port
   sites:                # Registered sites for file-based enhancement
     - site_id: "demo"
-      path: "./test-sites/demo-site"
+      path: "./test-sites/demo-site_enhanced"
       domain: "localhost:3000"
       auto_enhance: true
       backup_originals: true
-    - site_id: "dan-eden-test"
-      path: "./test-sites/simple/dan-eden-portfolio"
-      domain: "localhost:3001"
+    - site_id: "simple"
+      path: "./test-sites/simple/test-simple_enhanced"
+      domain: "localhost:3000"
+      auto_enhance: true
+      backup_originals: true
+    - site_id: "dan-eden"
+      path: "./test-sites/simple/dan-eden-portfolio_enhanced"
+      domain: "localhost:3000"
       auto_enhance: true
       backup_originals: true
     # Example additional site configuration: