Add instance nav prefs, env config UI, and PM2 restart.

P1-P4: configurable nav/section visibility in system settings, full .env editor with restart badges, password change, runtime hot overrides, and single-instance pm2 restart. Works in hub embed iframe.
Co-authored-by: Cursor <cursoragent@cursor.com>

lib/instance/templates/password_settings_panel.html

@@ -0,0 +1,15 @@
+{# 系统设置 · 账户密码 #}
+<div class="card settings-subcard settings-subcard--ops" id="password-settings-card" data-settings-section="password">
+    <h3 class="settings-subcard-title">账户密码修改</h3>
+    <p class="settings-subcard-desc">修改网页登录账号密码，写入 <code>.env</code> 后需重启实例生效。</p>
+    <div class="settings-password-form">
+        <label>当前密码 <input type="password" id="pwd-old" autocomplete="current-password"></label>
+        <label>新用户名（可选） <input type="text" id="pwd-new-username" autocomplete="username"></label>
+        <label>新密码 <input type="password" id="pwd-new" autocomplete="new-password"></label>
+        <label>确认新密码 <input type="password" id="pwd-confirm" autocomplete="new-password"></label>
+    </div>
+    <div class="settings-actions-row">
+        <button type="button" class="btn-primary btn-sm" id="pwd-save-btn">保存密码</button>
+        <span class="settings-status-line" id="pwd-save-status"></span>
+    </div>
+</div>