Simplify development workflow and fix content editing conflicts

- Replace complex multi-server setup (live-server + API) with unified Go server
- Serve all sites at /sites/{site_id} endpoints, eliminating port conflicts
- Fix content-type middleware to serve proper MIME types for static files
- Prevent script injection duplication with future-proof CDN-compatible detection
- Remove auto page reload from enhance button to eliminate editing interruptions
- Enable seamless content editing workflow with manual enhancement control

Development now requires only 'just dev' instead of complex demo commands.
All sites immediately available at localhost:8080 without hot reload conflicts.

lib/src/core/auth.js

@@ -644,10 +644,11 @@ export class InsertrAuth {
             // Show success state briefly
             enhanceBtn.textContent = '✅ Enhanced!';
             
-            // Optional: Trigger page reload to show enhanced files
+            // Reset button after success (no page reload needed)
             setTimeout(() => {
-                window.location.reload();
-            }, 1000);
+                enhanceBtn.textContent = '🔄 Enhance';
+                enhanceBtn.disabled = false;
+            }, 2000);
 
         } catch (error) {
             console.error('❌ Enhancement failed:', error);