feat: guide first mobile task activation (Closes #1140)

frontend/index.html

@@ -1829,6 +1829,22 @@
   </section>
 </dialog>
 
+<dialog class="mobile-first-task" id="mobile-first-task" aria-labelledby="mobile-first-task-title">
+  <section class="mobile-first-task-panel">
+    <header>
+      <div><p class="small muted">Welcome to Work</p><h2 id="mobile-first-task-title">Start your first task</h2></div>
+      <button id="close-mobile-first-task" type="button">Close</button>
+    </header>
+    <p class="small">Choose work, start it, then return to Work whenever you want to continue.</p>
+    <p id="mobile-first-task-status" class="small" role="status" aria-live="polite"></p>
+    <div class="mobile-first-task-actions">
+      <button id="mobile-first-task-find" type="button">Find a task</button>
+      <button id="mobile-first-task-create" type="button">Create a task</button>
+      <button id="mobile-first-task-setup" type="button">Make this phone work-ready</button>
+    </div>
+  </section>
+</dialog>
+
 <nav class="mobile-task-dock" id="mobile-task-dock" aria-label="Primary tasks">
   <button class="mobile-task-action" data-mobile-task="work" type="button" aria-current="page"><span id="mobile-work-label">Work</span></button>
   <button class="mobile-task-action" data-mobile-task="find" type="button">Find</button>
@@ -1933,6 +1949,7 @@
 <script src="static/mobile-today-command-bar.js"></script>
 <script src="static/mobile-task-dock.js"></script>
 <script src="static/mobile-pull-refresh.js"></script>
+<script src="static/mobile-first-task.js"></script>
 <script src="static/mobile-work-entry.js"></script>
 <script src="static/mobile-queue-launcher.js"></script>
 <script src="static/mobile-delivery-recovery.js"></script>