feat: keep Week Ahead available offline (Closes #1218)

frontend/index.html

@@ -509,6 +509,8 @@
       <div class="small">Seven-day overview</div>
       <h2 id="week-review-title">Week Ahead</h2>
       <p class="small muted">See what is next and check each day’s load. Edit only when you are ready.</p>
+      <p class="week-offline-snapshot" id="week-offline-snapshot" role="status" aria-live="polite" hidden></p>
+      <button id="retry-week-live" type="button" hidden>Retry live Week Ahead</button>
       <button id="open-week-capacity-import" type="button">Set capacity from calendar</button>
       <div class="week-review-duplicates" id="week-review-duplicates" role="alert" hidden></div>
       <div class="week-review-days" id="week-review-days"></div>