feat: coach first mobile task to completion (Closes #1146)

frontend/index.html

@@ -1655,12 +1655,19 @@
 </section>
 
 <section class="mobile-today-hud" data-mobile-today-hud aria-label="Active Today session" hidden>
+  <div class="mobile-first-task-coach small" data-mobile-first-task-coach hidden>
+    <strong>Complete your first task</strong>
+    <span>Open it, then use Done &amp; next after a real outcome.</span>
+  </div>
   <button class="mobile-today-summary" data-mobile-today-open type="button" aria-label="Open current Today item"></button>
   <div class="small" data-work-session-progress aria-live="polite"></div>
   <button data-mobile-today-complete type="button" hidden>Done &amp; next</button>
   <button data-mobile-today-toggle data-work-session-timer-toggle type="button">Pause timer</button>
   <button data-mobile-today-more type="button" aria-controls="mobile-today-actions" aria-haspopup="dialog">More</button>
 </section>
+<div class="mobile-first-task-receipt" id="mobile-first-task-receipt" role="status" aria-live="polite" hidden>
+  First task completed · continue Today
+</div>
 <dialog class="mobile-today-actions" id="mobile-today-actions" aria-modal="true" aria-labelledby="mobile-today-actions-title">
   <section class="mobile-today-actions-panel">
     <header><h2 id="mobile-today-actions-title">Today session</h2><button data-mobile-today-actions-close type="button">Close</button></header>