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/content/site_manager.go

@@ -105,23 +105,12 @@ func (sm *SiteManager) GetAllSites() map[string]*SiteConfig {
 }
 
 // IsAutoEnhanceEnabled checks if a site has auto-enhancement enabled
-// Returns false in development mode to prevent unwanted file modifications and live-reload loops
 func (sm *SiteManager) IsAutoEnhanceEnabled(siteID string) bool {
-	sm.mutex.RLock()
-	defer sm.mutex.RUnlock()
-
-	// Disable auto-enhancement in development mode to prevent file modification conflicts with live-reload
+	// Never auto-enhance in development mode - use manual enhance button instead
 	if sm.devMode {
 		return false
 	}
 
-	site, exists := sm.sites[siteID]
-	return exists && site.AutoEnhance
-}
-
-// ForceEnhanceEnabled allows testing production behavior in development mode
-// This method bypasses the dev_mode check for testing purposes
-func (sm *SiteManager) ForceEnhanceEnabled(siteID string) bool {
 	sm.mutex.RLock()
 	defer sm.mutex.RUnlock()