feat(workspace): implement Yjs CRDT real-time collaborative editing (resolves FLAW-01)

frontend/src/lib/api.ts

@@ -602,6 +602,17 @@ export const api = {
     };
   },
 
+  async getDocumentCRDT(id: string): Promise<{ docId: string; state?: string; updates?: string[] }> {
+    return request<{ docId: string; state?: string; updates?: string[] }>(`/api/v1/documents/${id}/crdt`);
+  },
+
+  async saveDocumentCRDT(id: string, state: string): Promise<{ success: boolean }> {
+    return request<{ success: boolean }>(`/api/v1/documents/${id}/crdt`, {
+      method: 'PUT',
+      body: JSON.stringify({ state }),
+    });
+  },
+
   async deleteDocument(id: string): Promise<void> {
     await request(`/api/v1/documents/${id}`, { method: 'DELETE' });
   },