fix: enable section click functionality for edit UI

- Fixed conflicting DOMContentLoaded handlers that were overwriting section content
- Added modular component detection to prevent content rendering conflicts
- Updated initialization to use markdown content directly instead of empty container
- Verified complete functionality: sections clickable, floating menu appears, accept/cancel buttons work

Root cause: Two competing event handlers were initializing content differently,
causing sections to be overwritten by direct HTML rendering.

Solution: Added component detection guard and proper content initialization.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

markitect/clean_document_manager.py

@@ -1104,9 +1104,16 @@ class CleanDocumentManager:
         document.addEventListener('DOMContentLoaded', function() {{
             console.log("Rendering content...");
 
+            // Check if modular components are being used
+            if (typeof SectionManager !== 'undefined') {{
+                console.log("✓ Modular components detected - skipping direct content rendering");
+                console.log("✓ Content will be rendered by modular architecture");
+                return;
+            }}
+
             const contentDiv = document.getElementById('markdown-content');
 
-            // Step 1: Ensure content is always displayed
+            // Step 1: Ensure content is always displayed (fallback for non-modular mode)
             if (contentDiv) {{
                 if (typeof marked !== 'undefined') {{
                     try {{
@@ -1259,11 +1266,14 @@ document.addEventListener('DOMContentLoaded', function() {
         debugPanel.addMessage(`Changes cancelled for section: ${data.sectionId}`, 'WARNING');
     });
 
-    // Initialize with existing markdown content if present
-    const existingContent = container.textContent || container.innerText || '';
-    if (existingContent.trim()) {
-        const sections = sectionManager.createSectionsFromMarkdown(existingContent);
+    // Initialize with markdown content
+    const markdownToRender = markdownContent || '';
+    if (markdownToRender.trim()) {
+        const sections = sectionManager.createSectionsFromMarkdown(markdownToRender);
         domRenderer.renderAllSections(sections);
+        debugPanel.addMessage(`Initialized with ${sections.length} sections`, 'INFO');
+    } else {
+        debugPanel.addMessage('No markdown content to initialize', 'WARNING');
     }
 
     // Make components globally available for debugging