sync: Major UI updates from private repo (Jan 16-24)

Features synced:
- UI Panels Refactor: flexible pane system with ChatPane, NodePane,
  DimensionsPane, WorkflowsPane, ViewsPane, MapPane
- Source Content Reader: content type detection + 4 formatters
  (transcript, book, markdown, raw)
- Source Content Search: Cmd+F search in Source Reader
- Feed Layout Overhaul: LeftToolbar, SplitHandle, CollapsedRail
- Map Panel: promoted to first-class pane
- Edge policy simplification: auto-inference + direction correction

New files:
- src/components/panes/* (pane system)
- src/components/layout/CollapsedRail.tsx
- src/components/layout/LeftToolbar.tsx
- src/components/layout/SplitHandle.tsx
- src/components/focus/source/* (Source Reader + formatters)
- src/components/views/ViewsOverlay.tsx

Updated:
- ThreePanelLayout.tsx (complete refactor)
- FocusPanel.tsx (Source tab integration)
- API routes (dimensions GET, edges auto-inference)
- Database services (nodes, edges, dimensions)

Dependencies added:
- react-markdown
- remark-gfm

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/focus/dimensions/DimensionTags.tsx

@@ -90,14 +90,31 @@ export default function DimensionTags({
     }
   };
 
-  const addDimension = async (dimension: string) => {
+  const addDimension = async (dimension: string, description?: string) => {
     if (!dimension.trim() || dimensions.includes(dimension.trim())) {
       return;
     }
 
+    // If description is provided, create/update the dimension in the database first
+    if (description) {
+      try {
+        await fetch('/api/dimensions', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({
+            name: dimension.trim(),
+            description: description.trim(),
+            isPriority: false
+          })
+        });
+      } catch (error) {
+        console.error('Error creating dimension with description:', error);
+      }
+    }
+
     const newDimensions = [...dimensions, dimension.trim()];
     await onUpdate(newDimensions);
-    
+
     setSearchQuery('');
     setSuggestions([]);
     setIsAdding(false);
@@ -387,8 +404,8 @@ export default function DimensionTags({
       <DimensionSearchModal
         isOpen={isAdding}
         onClose={() => setIsAdding(false)}
-        onDimensionSelect={(dim) => {
-          addDimension(dim);
+        onDimensionSelect={(dim, description) => {
+          addDimension(dim, description);
         }}
         existingDimensions={dimensions}
       />