feat: final schema pass — sync 9 schema changes from main repo

- Rename nodes.content → nodes.notes across all services, tools, API routes, and UI
- Add dimensions.icon column support (GET/POST routes, types)
- Add nodes.event_date column (create/update flows, types)
- Drop nodes.type and nodes.is_pinned references
- Drop edges.user_feedback references
- Drop chat_memory_state table (replaced with DROP IF EXISTS in migration)
- Update schema guide files (system/schema.md)
- Add runtime migration block in sqlite-client.ts for existing databases
- Fix MCP tool schemas (external API keeps 'content' param, maps to 'notes' internally)
- Update standalone MCP server (nodeService.js, sqlite-client.js, index.js)
- Update HTTP MCP server (server.js, stdio-server.js)
- Update all extraction tools (paper, website, youtube)
- Update all UI components (FocusPanel, ThreePanelLayout, GridView, ListView, FolderViewOverlay)
- TypeScript: 0 errors

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/api/nodes/[id]/route.ts

@@ -68,16 +68,11 @@ export async function PUT(
       }, { status: 404 });
     }
 
-    if (body && Object.prototype.hasOwnProperty.call(body, 'is_pinned')) {
-      console.warn(`[nodes/${nodeId}] Ignoring legacy is_pinned payload`);
-      delete body.is_pinned;
-    }
-
     const updates: Record<string, unknown> = { ...body };
     let shouldQueueEmbed = false;
 
     const incomingChunk = typeof body.chunk === 'string' ? body.chunk : undefined;
-    const incomingContent = typeof body.content === 'string' ? body.content : undefined;
+    const incomingNotes = typeof body.notes === 'string' ? body.notes : undefined;
     const existingChunk = existingNode.chunk ?? '';
 
     if (incomingChunk !== undefined) {
@@ -92,8 +87,8 @@ export async function PUT(
       } else {
         delete updates.chunk_status;
       }
-    } else if (!existingChunk.trim() && hasSufficientContent(incomingContent)) {
-      updates.chunk = incomingContent;
+    } else if (!existingChunk.trim() && hasSufficientContent(incomingNotes)) {
+      updates.chunk = incomingNotes;
       updates.chunk_status = 'not_chunked';
       shouldQueueEmbed = true;
     }