feat(scheduling): persist notifications, batch notify flow, dedup protection

- Add tab_scheduling_notifications table with bootstrap via ensureSchedulingTables()
- Notify endpoint rewritten: dedup by (suggestion_id, candidate_plate), history list, PATCH /:id for execute/cancel lifecycle
- Batch notify endpoint returns success/skipped/failed counts
- Suggestions response now carries notificationId + notificationStatus per candidate (joined from active-notification map)
- UI: select mode with checkboxes, floating action bar, confirmation modal listing each swap; already-notified items are dimmed and skipped
- Detail view badges show sent/executed state, preventing duplicate notify

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/modules/scheduling/SuggestionDetail.tsx

@@ -65,7 +65,10 @@ export default function SuggestionDetail({ suggestion: s, onClose, onNotifySucce
   };
 
   const renderCandidate = (c: CandidateVehicle) => {
-    const sent = sentPlates.has(c.plateNumber);
+    const sent =
+      sentPlates.has(c.plateNumber) ||
+      c.notificationStatus === 'sent' ||
+      c.notificationStatus === 'executed';
     return (
       <div key={c.plateNumber} className="rounded-xl border border-slate-200 overflow-hidden bg-white">
         <div className="flex items-center justify-between px-3 py-2">