fix: restrict auto-accept to plan mode only, block AskUserQuestion prompts

The auto-accept feature was too aggressive - it would press Enter for any
silence without a completion message, including AskUserQuestion prompts.
Now uses the elicitation_dialog notification hook to detect when Claude is
asking a question, and blocks auto-accept in that case. Only plan mode
approvals (silence with no completion message AND no elicitation signal)
trigger auto-accept.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/web/public/index.html

@@ -338,11 +338,11 @@
             </div>
 
             <div class="form-row">
-              <label>Auto-Accept Prompts</label>
+              <label>Auto-Accept Plan Mode</label>
               <div class="checkbox-group-inline">
                 <label class="checkbox-inline">
                   <input type="checkbox" id="modalRespawnAutoAccept" checked onchange="app.autoSaveRespawnConfig()">
-                  <span>Accept plan mode &amp; questions</span>
+                  <span>Accept plan mode approvals</span>
                 </label>
               </div>
               <span class="form-hint">Presses Enter to accept plan approvals and default question options when Claude is waiting</span>