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>

e2e/share.e2e.mjs

@@ -45,13 +45,18 @@ async function openDoc(browser, token, title) {
 }
 
 const TITLE = `Freigabe-Test ${Date.now()}`;
+const TODO_ID = `fr_todo_${Date.now()}`;
+const TODO_TEXT = `Rollup-Aufgabe ${Date.now()}`;
 
 const main = async () => {
   const admin = (await api(null, 'POST', '/api/v1/auth/login', { login: 'admin', password: 'admin' })).token;
   const user = (await api(null, 'POST', '/api/v1/auth/login', { login: 'user', password: 'user' })).token;
   const doc = await api(admin, 'POST', '/api/v1/documents', {
     title: TITLE,
-    blocks: [{ id: `fr_${Date.now()}`, type: 'bullet', content: 'Vom Eigentümer', level: 0 }],
+    blocks: [
+      { id: `fr_${Date.now()}`, type: 'bullet', content: 'Vom Eigentümer', level: 0 },
+      { id: TODO_ID, type: 'todo', content: TODO_TEXT, level: 0 },
+    ],
   });
 
   const browser = await chromium.launch();
@@ -97,6 +102,18 @@ const main = async () => {
   }, 6000);
   check(!!saved, 'Bearbeiter kann die geteilte Notiz bearbeiten');
 
+  // Ticking a to-do in the overview goes through the sync endpoint as well
+  await A.page.bringToFront();
+  await A.page.getByRole('button', { name: 'Schließen', exact: true }).last().click(); // the share dialog is still open
+  await A.page.locator('button:visible', { hasText: 'To-Dos' }).first().click();
+  await A.page.getByTitle('Alle To-Dos als einfache Liste').click();
+  await A.page.locator('div', { hasText: TODO_TEXT }).last().locator('button').first().click();
+  const ticked = await waitFor(async () => {
+    const s = await api(admin, 'GET', `/api/v1/docs/${doc.id}/snapshot`);
+    return s.blocks.find((b) => b.id === TODO_ID)?.props?.checked === true;
+  }, 5000);
+  check(!!ticked, 'Abhaken in der To-Do-Übersicht wird gespeichert');
+
   await browser.close();
   console.log(failures ? `${failures} FEHLGESCHLAGEN` : 'ALLE PRÜFUNGEN BESTANDEN');
   process.exit(failures ? 1 : 0);