fixes: collab move, caldav abort, draft recovery, autobackup, test stabilization

- Collab: moving a shared card to a local bucket no longer deletes it
  (clear relay_uid before tombstone echo returns)
- CalDAV: abort sync on remote fetch failure instead of treating all
  local cards as remotely-deleted
- Editor: autobackup drafts to localStorage with restore prompt on
  re-open (skipped during tests)
- Cards POST: persist scratchpad and due_date (was dropped on create)
- Disable spellcheck/autocorrect on editor inputs
- Test runner: purge leftover __prefix__ cards/buckets + editor drafts
  before every run (cleans up from failed previous runs)
- Stabilize mark-done, group-delete, undo-body tests with poll loops

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/plugins/tests/card-interactions.test.js

@@ -157,14 +157,26 @@ describe('Card: Context Menu Actions', () => {
         expect(doneBtn.textContent.toLowerCase()).toContain('mark done');
 
         click(doneBtn);
-        await sleep(300);
-        let updated = await fetch(`api/cards?ids=${res.id}`).then(r => r.json());
+        // Poll until #done is persisted to the DB
+        let updated;
+        for (let i = 0; i < 40; i++) {
+            await sleep(100);
+            updated = await fetch(`api/cards?ids=${res.id}`).then(r => r.json());
+            if ((updated[0]?.tags || '').includes('done')) break;
+        }
         expect((updated[0].body || '').toLowerCase()).toContain('#done');
         expect(updated[0].tags || '').toContain('done');
 
+        // Wait for the board to re-render with the updated card data
+        for (let i = 0; i < 20; i++) {
+            const card = window.state?.cards?.find(c => c.id == res.id);
+            if (card && (card.tags || '').includes('done')) break;
+            await sleep(100);
+        }
+
         // Re-open menu — the entry should now flip to "Unmark done"
         rightClick(document.querySelector(`[data-id="${res.id}"]`));
-        await sleep(150);
+        await sleep(200);
         const doneBtn2 = $$('#ctx-items [data-action="due-done"]')[0];
         expect(doneBtn2.textContent.toLowerCase()).toContain('unmark');
 
@@ -331,11 +343,16 @@ describe('Card: Group Delete', () => {
             // Confirm the delete
             const okBtn = document.getElementById('dialog-ok');
             if (okBtn) click(okBtn);
-            await sleep(500);
         }
 
-        // All three cards should be gone
-        const remaining = await fetch('api/cards').then(r => r.json());
+        // Poll until all three cards are gone (group delete = N serial DELETEs)
+        let remaining;
+        for (let i = 0; i < 40; i++) {
+            await sleep(100);
+            remaining = await fetch('api/cards').then(r => r.json());
+            const stillThere = remaining.some(c => c.id === parent.id || c.id === child1.id || c.id === child2.id);
+            if (!stillThere) break;
+        }
         expect(remaining.some(c => c.id === parent.id)).toBe(false);
         expect(remaining.some(c => c.id === child1.id)).toBe(false);
         expect(remaining.some(c => c.id === child2.id)).toBe(false);