feat: auto-accept plan mode and question prompts in respawn controller

When Claude enters plan mode or asks a question (AskUserQuestion), output
stops without a completion message. The new autoAcceptPrompts feature
detects this state and sends Enter after a configurable delay (default 8s)
to accept the plan or select the default option, keeping Claude working
autonomously.

Enabled by default. Adds UI checkbox in the respawn config panel.
Safety: only fires once per silence period, requires prior output,
and won't fire during active respawn cycles.

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

src/web/public/index.html

@@ -333,6 +333,17 @@
               <span class="form-hint">Sent only when /init completes but Claude stays idle</span>
             </div>
 
+            <div class="form-row">
+              <label>Auto-Accept Prompts</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>
+                </label>
+              </div>
+              <span class="form-hint">Presses Enter to accept plan approvals and default question options when Claude is waiting</span>
+            </div>
+
             <div class="form-row">
               <label>Auto-Compact Context</label>
               <div class="auto-clear-row">