fix: align MCP server schema with memento-note + per-request user isolation

- Remove `embedding` column from MCP Note model (dropped by migration 20260425120000)
- Add missing columns: trashedAt, dismissedFromRecent, contentUpdatedAt, cardSizeMode
- Add NoteEmbedding model and Label.notebook relation
- Use AsyncLocalStorage to pass authenticated userId from API key to tool handlers
- Enable SSE mode and auth in docker-compose for N8N integration

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

mcp-server/request-context.js

@@ -0,0 +1,7 @@
+import { AsyncLocalStorage } from 'async_hooks';
+
+/**
+ * Per-request context storage for passing authenticated userId
+ * from Express middleware to MCP tool handlers.
+ */
+export const requestContext = new AsyncLocalStorage();