feat: add manual file enhancement with development mode support

- Add manual enhance API endpoint (POST /api/enhance?site_id={site}) for triggering file enhancement
- Implement enhance button in JavaScript library status indicator (🔄 Enhance)
- Disable auto-enhancement in development mode to prevent live-reload conflicts
- Add dev mode parameter to SiteManager to control enhancement behavior
- Update API routing structure to support /api/enhance endpoint
- Include enhance button styling and user feedback (loading, success, error states)
- Button triggers file enhancement and page reload to show updated static files

Development workflow improvements:
- Content edits → Immediate editor preview (no unwanted page reloads)
- Manual enhance button → Intentional file updates + reload for testing
- Production mode maintains automatic enhancement on content changes

This resolves the live-reload conflict where automatic file enhancement
was causing unwanted page reloads during content editing in development.

internal/api/handlers.go

@@ -40,6 +40,53 @@ func (h *ContentHandler) SetSiteManager(siteManager *content.SiteManager) {
 	h.siteManager = siteManager
 }
 
+// EnhanceSite handles POST /api/enhance - manual site enhancement trigger
+func (h *ContentHandler) EnhanceSite(w http.ResponseWriter, r *http.Request) {
+	siteID := r.URL.Query().Get("site_id")
+	if siteID == "" {
+		http.Error(w, "site_id parameter is required", http.StatusBadRequest)
+		return
+	}
+
+	if h.siteManager == nil {
+		http.Error(w, "Site manager not available", http.StatusServiceUnavailable)
+		return
+	}
+
+	// Check if site is registered
+	site, exists := h.siteManager.GetSite(siteID)
+	if !exists {
+		http.Error(w, fmt.Sprintf("Site %s is not registered", siteID), http.StatusNotFound)
+		return
+	}
+
+	// Perform enhancement
+	err := h.siteManager.EnhanceSite(siteID)
+	if err != nil {
+		log.Printf("❌ Manual enhancement failed for site %s: %v", siteID, err)
+		http.Error(w, fmt.Sprintf("Enhancement failed: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	// Get enhancement statistics
+	stats := h.siteManager.GetStats()
+
+	// Return success response with details
+	response := map[string]interface{}{
+		"success":   true,
+		"site_id":   siteID,
+		"site_path": site.Path,
+		"message":   fmt.Sprintf("Successfully enhanced site %s", siteID),
+		"stats":     stats,
+		"timestamp": time.Now().Format(time.RFC3339),
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(response)
+
+	log.Printf("✅ Manual enhancement completed for site %s", siteID)
+}
+
 // GetContent handles GET /api/content/{id}
 func (h *ContentHandler) GetContent(w http.ResponseWriter, r *http.Request) {
 	vars := mux.Vars(r)