feat: start work from an empty mobile queue (Closes #691)

frontend/index.html

@@ -183,6 +183,16 @@
       <div class="small" id="queue-find-status" role="status" aria-live="polite"></div>
       <button id="search-older-work" type="button" hidden>Search older work</button>
     </form>
+    <section class="empty-work-start" id="empty-work-start" aria-labelledby="empty-work-start-heading" hidden>
+      <div>
+        <strong id="empty-work-start-heading">Ready for something new?</strong>
+        <p class="small muted">Find an available issue to own, or create the work that needs doing.</p>
+      </div>
+      <div class="empty-work-start-actions">
+        <button id="empty-work-find" type="button">Find and start work</button>
+        <button id="empty-work-create" type="button">Create an issue</button>
+      </div>
+    </section>
     <div class="my-work-list" id="my-work-list"></div>
     <div class="small" id="work-page-status" aria-live="polite"></div>
     <button class="load-more-work" id="load-more-work" type="button" hidden>Load older work</button>