feat: Implement syntactic sugar and site-specific discovery config

- Add syntactic sugar for container transformation: .insertr containers → children get .insertr
- Fix discovery auto-running when disabled with site-specific config loading
- Add comprehensive styling test examples for HTML attribute preservation
- Include test input for syntactic sugar validation
- Update discovery defaults to respect developer intent (disabled by default)

insertr.yaml

@@ -16,18 +16,30 @@ server:
       path: "./demos/default_enhanced"
       source_path: "./demos/default"
       auto_enhance: true
+      discovery:
+        enabled: false    # Uses explicit class="insertr" markings
+        aggressive: false
     - site_id: "simple"
       path: "./demos/simple_enhanced"
       source_path: "./demos/simple"
       auto_enhance: true
+      discovery:
+        enabled: false    # Uses explicit class="insertr" markings
+        aggressive: false
     - site_id: "dan-eden-portfolio"
       path: "./demos/dan-eden-portfolio_enhanced"
       source_path: "./demos/dan-eden-portfolio"
       auto_enhance: true
+      discovery:
+        enabled: true     # Auto-discover elements (no explicit markings)
+        aggressive: false
     - site_id: "devigo-web"
       path: "./demos/devigo-web_enhanced"
       source_path: "./demos/devigo-web"
       auto_enhance: true
+      discovery:
+        enabled: false    # Uses explicit class="insertr" markings
+        aggressive: false
     # Example additional site configuration:
     # - site_id: "mysite"
     #   path: "/var/www/mysite"