fix: 修复上传按钮消失 + 移动流量面板HTML至script外

根因: 上一提交将traffic panel HTML放在</script>之前,
导致HTML被解析为JS代码,引发'Unexpected token <'错误,
handleFiles等函数未定义,上传功能完全失效

修复: 将traffic panel HTML移至</script>之后,{% endblock %}之前

验证: 14/14 Playwright测试通过 (上传/筛选/聚类/地图/边/节点/流量面板/社区焦点)

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

simple_analysis/templates/simple_analysis/simple_analysis.html

@@ -2839,7 +2839,9 @@ function escapeHtml(str) {
     return String(str).replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;');
 }
 
-<!-- Traffic Flow Panel -->
+</script>
+
+<!-- Traffic Flow Panel (outside script block) -->
 <div class="sa-traffic-panel" id="saTrafficPanel">
     <div style="display:flex;justify-content:space-between;align-items:center;margin-bottom:0.5rem;">
         <b style="font-size:0.9rem;">🌊 动态流通 (北京时间)</b>
@@ -2869,5 +2871,4 @@ function escapeHtml(str) {
     <div class="sa-traffic-info" id="saTrafficInfo"></div>
     <canvas id="saTrafficCanvas" class="sa-traffic-canvas" style="display:none;"></canvas>
 </div>
-</script>
 {% endblock %}