feat(调试): 测试页新增重绘分辨率选项

- app.py 调试接口新增 redraw_max_side 参数，控制整条管线的降分辨率
- debug_grow_timing.html 新增"重绘分辨率"下拉(640/768/896/1024/原图)
- 实测: 640比896省1.5s(5.2s vs 6.7s), 1024比896慢0.6s

static/debug_grow_timing.html

@@ -91,6 +91,17 @@
           <option value="30">30</option>
         </select>
       </div>
+      <div class="form-group">
+        <label>重绘分辨率</label>
+        <select id="redrawMaxSide">
+          <option value="">默认(896)</option>
+          <option value="640">640 (最快)</option>
+          <option value="768">768</option>
+          <option value="896">896</option>
+          <option value="1024">1024 (高画质)</option>
+          <option value="0">原图(不缩)</option>
+        </select>
+      </div>
       <button class="btn btn-primary" id="submitBtn" onclick="submitTest()">🚀 开始分析</button>
     </div>
     <div id="statusBar" class="status hidden"></div>
@@ -128,6 +139,8 @@ async function submitTest(){
   fd.append('hair_style', $('hairStyle').value);
   const _steps = $('webuiSteps').value;
   if(_steps !== '') fd.append('webui_steps', _steps);
+  const _side = $('redrawMaxSide').value;
+  if(_side !== '') fd.append('redraw_max_side', _side);
 
   try{
     const r = await fetch(API_BASE+'/api/v1/debug/grow-timing',{