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/agents/RAHChat.tsx

@@ -22,10 +22,17 @@ const createVoiceRequestId = () =>
     ? crypto.randomUUID()
     : `voice_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`;
 
+interface HighlightedPassage {
+  selectedText: string;
+  nodeId: number;
+  nodeTitle: string;
+}
+
 interface RAHChatProps {
   openTabsData: Node[];
   activeTabId: number | null;
   activeDimension?: string | null;
+  onClearDimension?: () => void;
   onNodeClick?: (nodeId: number) => void;
   delegations?: AgentDelegation[];
   messages?: ChatMessage[];
@@ -33,12 +40,16 @@ interface RAHChatProps {
   mode?: 'easy' | 'hard';
   delegationMode?: boolean;
   delegationSessionId?: string;
+  onQuickAdd?: () => void;
+  highlightedPassage?: HighlightedPassage | null;
+  onClearPassage?: () => void;
 }
 
 export default function RAHChat({
   openTabsData,
   activeTabId,
   activeDimension,
+  onClearDimension: _onClearDimension,
   onNodeClick,
   delegations = [],
   messages: externalMessages,
@@ -46,6 +57,9 @@ export default function RAHChat({
   mode = 'easy',
   delegationMode = false,
   delegationSessionId,
+  onQuickAdd: _onQuickAdd,
+  highlightedPassage: _highlightedPassage,
+  onClearPassage: _onClearPassage,
 }: RAHChatProps) {
   // Use external state if provided (lifted state), otherwise use local state
   const [internalMessages, internalSetMessages] = useState<ChatMessage[]>([]);