feat: frps-manager v1.0 - frp 0.70.1 multi-tenant web management system

- Multi-tenant client/proxy management with Flask+SQLite
- Frps server control (start/restart/token rotation)
- Generate frpc.ini with shared server token + admin API
- Dashboard API integration (live client/proxy status)
- RBAC: admin/tenant_admin/user roles
- Audit logging for all operations
- Systemd service files included
- Requires legacy INI format (frp 0.70 TOML auth broken)

templates/login.html

@@ -0,0 +1,14 @@
+{% extends "base.html" %}
+{% block title %}登录 · frps-manager{% endblock %}
+{% block content %}
+<div class="login-card">
+  <h1>frps-manager</h1>
+  <p class="muted">frp 内网穿透 Web 管理控制台</p>
+  <form method="post">
+    <label>用户名 <input name="username" autofocus required></label>
+    <label>密码 <input name="password" type="password" required></label>
+    <button type="submit" class="btn btn-primary">登录</button>
+  </form>
+  <p class="muted small">默认管理员 admin / admin（首次登录后请立刻改密）</p>
+</div>
+{% endblock %}