feat: Complete HTML-first architecture implementation with API integration

- Replace value field with html_content for direct HTML storage
- Add original_template field for style detection preservation
- Remove all markdown processing from injector (delete markdown.go)
- Fix critical content extraction/injection bugs in engine
- Add missing UpdateContent PUT handler for content persistence
- Fix API client field names and add updateContent() method
- Resolve content type validation (only allow text/link types)
- Add UUID-based ID generation to prevent collisions
- Complete first-pass processing workflow for unprocessed elements
- Verify end-to-end: Enhancement → Database → API → Editor → Persistence

All 37 files updated for HTML-first content management system.
Phase 3a implementation complete and production ready.

internal/engine/injector.go

@@ -12,7 +12,6 @@ import (
 type Injector struct {
 	client       ContentClient
 	siteID       string
-	mdProcessor  *MarkdownProcessor
 	authProvider *AuthProvider
 }
 
@@ -21,7 +20,6 @@ func NewInjector(client ContentClient, siteID string) *Injector {
 	return &Injector{
 		client:       client,
 		siteID:       siteID,
-		mdProcessor:  NewMarkdownProcessor(),
 		authProvider: &AuthProvider{Type: "mock"}, // default
 	}
 }
@@ -34,7 +32,6 @@ func NewInjectorWithAuth(client ContentClient, siteID string, authProvider *Auth
 	return &Injector{
 		client:       client,
 		siteID:       siteID,
-		mdProcessor:  NewMarkdownProcessor(),
 		authProvider: authProvider,
 	}
 }
@@ -53,17 +50,8 @@ func (i *Injector) InjectContent(element *Element, contentID string) error {
 		return nil
 	}
 
-	// Replace element content based on type
-	switch element.Type {
-	case "text":
-		i.injectTextContent(element.Node, contentItem.Value)
-	case "markdown":
-		i.injectMarkdownContent(element.Node, contentItem.Value)
-	case "link":
-		i.injectLinkContent(element.Node, contentItem.Value)
-	default:
-		i.injectTextContent(element.Node, contentItem.Value)
-	}
+	// Direct HTML injection for all content types
+	i.injectHTMLContent(element.Node, contentItem.HTMLContent)
 
 	// Add data attributes for editor functionality
 	i.AddContentAttributes(element.Node, contentID, element.Type)
@@ -97,65 +85,13 @@ func (i *Injector) InjectBulkContent(elements []ElementWithID) error {
 			continue
 		}
 
-		// Replace content based on type
-		switch elem.Element.Type {
-		case "text":
-			i.injectTextContent(elem.Element.Node, contentItem.Value)
-		case "markdown":
-			i.injectMarkdownContent(elem.Element.Node, contentItem.Value)
-		case "link":
-			i.injectLinkContent(elem.Element.Node, contentItem.Value)
-		default:
-			i.injectTextContent(elem.Element.Node, contentItem.Value)
-		}
+		// Direct HTML injection for all content types
+		i.injectHTMLContent(elem.Element.Node, contentItem.HTMLContent)
 	}
 
 	return nil
 }
 
-// injectTextContent replaces text content in an element
-func (i *Injector) injectTextContent(node *html.Node, content string) {
-	// Remove all child nodes
-	for child := node.FirstChild; child != nil; {
-		next := child.NextSibling
-		node.RemoveChild(child)
-		child = next
-	}
-
-	// Add new text content
-	textNode := &html.Node{
-		Type: html.TextNode,
-		Data: content,
-	}
-	node.AppendChild(textNode)
-}
-
-// injectMarkdownContent handles markdown content - converts markdown to HTML
-func (i *Injector) injectMarkdownContent(node *html.Node, content string) {
-	if content == "" {
-		i.injectTextContent(node, "")
-		return
-	}
-
-	// Convert markdown to HTML using server processor
-	htmlContent, err := i.mdProcessor.ToHTML(content)
-	if err != nil {
-		log.Printf("⚠️ Markdown conversion failed for content '%s': %v, falling back to text", content, err)
-		i.injectTextContent(node, content)
-		return
-	}
-
-	// Inject the HTML content
-	i.injectHTMLContent(node, htmlContent)
-}
-
-// injectLinkContent handles link/button content with URL extraction
-func (i *Injector) injectLinkContent(node *html.Node, content string) {
-	// For now, just inject the text content
-	// TODO: Parse content for URL and text components
-	i.injectTextContent(node, content)
-}
-
 // injectHTMLContent safely injects HTML content into a DOM node
 // Preserves the original element and only replaces its content
 func (i *Injector) injectHTMLContent(node *html.Node, htmlContent string) {
@@ -172,8 +108,14 @@ func (i *Injector) injectHTMLContent(node *html.Node, htmlContent string) {
 	// Parse HTML string
 	doc, err := html.Parse(strings.NewReader(wrappedHTML))
 	if err != nil {
-		log.Printf("Failed to parse HTML content '%s': %v, falling back to text", htmlContent, err)
-		i.injectTextContent(node, htmlContent)
+		log.Printf("Failed to parse HTML content '%s': %v, falling back to text node", htmlContent, err)
+		// Fallback: inject as text node
+		i.clearNode(node)
+		textNode := &html.Node{
+			Type: html.TextNode,
+			Data: htmlContent,
+		}
+		node.AppendChild(textNode)
 		return
 	}