feat: add web admin panel for node management

Add Flask panel with login, add/delete nodes, and share link copy.
Generate sing-box config from SQLite; add uninstall script and clean install flow.
Panel served at https://DOMAIN:8444 via nginx.

Co-authored-by: Cursor <cursoragent@cursor.com>

panel/templates/dashboard.html

@@ -0,0 +1,65 @@
+{% extends "base.html" %}
+{% block title %}节点管理 · jiedian{% endblock %}
+{% block body %}
+<header class="topbar">
+  <div>
+    <strong>jiedian 面板</strong>
+    <span class="muted"> · {{ domain }}</span>
+  </div>
+  <a class="btn ghost" href="{{ url_for('logout') }}">退出</a>
+</header>
+
+<main class="container">
+  <section class="hero">
+    <div>
+      <h1>节点列表</h1>
+      <p class="muted">VPS {{ vps_ip }} · Reality 443 · Hysteria2 8443</p>
+    </div>
+    <button id="addBtn" class="btn primary">+ 添加节点</button>
+  </section>
+
+  <div id="toast" class="toast hidden"></div>
+  <div id="nodeList" class="node-list">
+    {% for node in nodes %}
+    <article class="node-card" data-id="{{ node.id }}">
+      <div class="node-head">
+        <h2>{{ node.name }}</h2>
+        <span class="tag">{{ node.created_at[:10] }}</span>
+      </div>
+      <div class="field">
+        <label>VLESS + Reality</label>
+        <div class="copy-row">
+          <input readonly value="{{ node.links.vless }}">
+          <button class="btn" data-copy="{{ node.links.vless }}">复制</button>
+        </div>
+      </div>
+      <div class="field">
+        <label>Hysteria2</label>
+        <div class="copy-row">
+          <input readonly value="{{ node.links.hy2 }}">
+          <button class="btn" data-copy="{{ node.links.hy2 }}">复制</button>
+        </div>
+      </div>
+      <div class="node-actions">
+        <button class="btn danger delete-btn" data-id="{{ node.id }}">删除</button>
+      </div>
+    </article>
+    {% endfor %}
+  </div>
+</main>
+
+<div id="modal" class="modal hidden">
+  <div class="modal-card">
+    <h3>添加节点</h3>
+    <label>节点名称</label>
+    <input id="nodeName" type="text" placeholder="例如：手机、电脑">
+    <div class="modal-actions">
+      <button id="cancelBtn" class="btn ghost">取消</button>
+      <button id="confirmAddBtn" class="btn primary">创建</button>
+    </div>
+  </div>
+</div>
+{% endblock %}
+{% block scripts %}
+<script src="{{ url_for('static', filename='app.js') }}"></script>
+{% endblock %}