fixes: scratchpad, zen ESC, chat time, tooltip safety, collab sync race

- Scratchpad: card-scoped private notes in editor (toggle vs preview),
  smaller font, cleared via button, stored in cards.scratchpad
- Zen mode: ESC exits zen before closing detail, Z toggles zen
- Chat: always show absolute time (hh:mm, yesterday, or date+time)
- Backspace/Delete also deletes focused card (not just selected)
- Selected + focused cards use brand accent (not accent2)
- Tooltip: guard against non-element targets
- Collab sync: skip poll while editor is open, 2s push debounce
- Rrule test: only check geburtstag tag, not title format

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

public/plugins/collab-buckets/collab-buckets.js

@@ -58,8 +58,15 @@ async function loadCollabMeta() {
     } catch (err) { /* silent; relay may be offline */ }
 }
 
+let pollLocked = false;
+
 async function pollOnce() {
+    if (pollLocked) return;
+    // Don't poll while user is actively editing — the push would race
+    // with the in-progress save and corrupt card state.
+    if (document.getElementById('modal')?.classList.contains('open')) return;
     try {
+        pollLocked = true;
         const res = await hyprcrd.api('api/collab-buckets/poll', { method: 'POST' });
         if (!res?.ok) return;
         if (res.self) window._collabSelf = res.self;
@@ -112,7 +119,7 @@ async function pollOnce() {
             const by = Array.isArray(res.card_stats?.blocked_by) ? res.card_stats.blocked_by : [];
             showBlockedToast(by);
         }
-    } catch { /* silent */ }
+    } catch { /* silent */ } finally { pollLocked = false; }
 }
 
 function showConflictToast(n) {