refactor(notes): remove legacy whole-document saves; all block changes go through sync

Phase 5 of the collaboration plan:
- Remove PATCH /documents/{id}/blocks, PatchDocumentBlocks, the
  DOC_BLOCKS_PATCHED event and its types, FlushDocumentState and
  LoadDocumentState. PUT /documents/{id} rejects blocks (400) and only
  changes title, icon, folder and pin; editors may now change title/icon.
- The to-do overview ticks via a single operation on /docs/{id}/sync
  (new skipLog flag). Task links set the block tick with a targeted
  operation and notify open editors; creating a linked task needs edit
  rights.
- Keep the three share tables: DocRole already decides centrally, and
  rewriting the visibility queries would only add risk (documented in plan).
- Tests adapted to the new paths; share e2e test now also ticks a to-do in
  the overview.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/lib/docSync/oneoff.ts

@@ -0,0 +1,18 @@
+// Sends a few operations for a note that is not open in an editor (e.g. ticking a to-do in the overview).
+// Goes through the same sync endpoint and rules as the editor, so the change is logged and pushed to
+// everyone who has the note open.
+import type { Op, Result } from './model';
+import { httpTransport } from './transport';
+
+export async function sendDocOps(docId: string, ops: Omit<Op, 'opId'>[]): Promise<Result[]> {
+  const bytes = new Uint8Array(8);
+  crypto.getRandomValues(bytes);
+  const clientId = `once_${Array.from(bytes, (b) => b.toString(16).padStart(2, '0')).join('')}`;
+  const res = await httpTransport.sync(docId, {
+    clientId,
+    lastSeq: 0,
+    ops: ops.map((op, i) => ({ ...op, opId: `${clientId}.${i}` }) as Op),
+    skipLog: true,
+  });
+  return res.results;
+}

frontend/src/lib/docSync/transport.ts

@@ -37,6 +37,7 @@ export interface SyncRequest {
   lastSeq: number;
   ops: Op[];
   leases?: { hold: string[]; release: string[] };
+  skipLog?: boolean; // one-off changes do not need the log back
 }
 
 export interface SyncResponse {