feat: BIND DNS Web Manager - Web interface for managing BIND9 DNS server

- Flask + SQLite web app with user authentication
- Zone management: create/delete zones, edit raw zone files
- Record management: add/delete A/AAAA/CNAME/MX/TXT/NS/PTR/SRV/CAA records
- Service control: start/stop/restart/reload BIND via systemctl/rndc
- Configuration editor: edit named.conf.options/local with syntax validation
- DNS query testing: online dig tool
- Audit log: all operations logged with user/timestamp
- BIND9 backend, listening on port 53

templates/login.html

@@ -0,0 +1,27 @@
+{% extends "base.html" %}
+{% block title %}登录 - DNS 管理{% endblock %}
+{% block content %}
+<div class="login-wrap">
+    <div class="login-card">
+        <div class="login-header">
+            <h1>🌐 DNS 管理系统</h1>
+            <p>BIND9 Web 管理界面</p>
+        </div>
+        <form method="POST" class="login-form">
+            <div class="form-group">
+                <label>用户名</label>
+                <input type="text" name="username" placeholder="admin" autofocus required>
+            </div>
+            <div class="form-group">
+                <label>密码</label>
+                <input type="password" name="password" placeholder="admin" required>
+            </div>
+            <button type="submit" class="btn btn-primary btn-block">登 录</button>
+        </form>
+        <div class="login-hint">
+            <p>默认账号: <code>admin</code> / <code>admin</code></p>
+            <p>首次登录后请修改密码</p>
+        </div>
+    </div>
+</div>
+{% endblock %}