Fix proxy/projects pages: error handling when API unavailable

- proxy: .catch() shows 'service not ready' instead of stuck loading
- projects: shows 'engine not ready' on API error
- Both: show 'no items' placeholder instead of blank

static/web_panel/pages/proxy.html

@@ -14,12 +14,14 @@
 
 <script>
 function refresh(){
-  fetch("/SenSu/api/proxy").then(r=>r.json()).then(d=>{
+  fetch("/SenSu/api/proxy").then(r=>{if(!r.ok)throw new Error(r.status);return r.json()}).then(d=>{
     var h="";
     for(var p of d.proxies||[]){
       h+='<div class="mgmt-card"><div class="status-dot status-running"></div><div class="info"><b>'+p.path+'</b><br><small>→ '+p.target+(p.description?" ("+p.description+")":"")+(p.external?" 🌐":"")+'</small></div><div class="actions"><button class="btn btn-sm btn-danger" onclick="delP(\"'+p.path+'\")">删除</button></div></div>';
     }
-    document.getElementById("proxy-list").innerHTML=h||"暂无代理"
+    document.getElementById("proxy-list").innerHTML=h||"<div style=\"color:var(--text-dim);text-align:center;padding:40px\">暂无代理配置</div>"
+  }).catch(function(e){
+    document.getElementById("proxy-list").innerHTML="<div style=\"color:var(--error);text-align:center;padding:40px\">代理服务未就绪 (API 返回 "+e.message+")</div>"
   })
 }
 function addP(){