feat: newapi-dashboard 全栈项目初始化

为 new-api (LLM API 网关) 构建独立前端管理面板:
- React 18 + TypeScript + Vite + Ant Design 5 前端
- Node.js + Express + better-sqlite3 BFF 后端
- 登录页: 站点选择器 + UserID + AccessToken 认证
- 仪表盘: 用户信息、额度环形图、7天趋势图、模型饼图、令牌概览、日志时间线
- 账单页: 筛选日志表格、模型消耗柱状图、充值记录、CSV/PDF 导出(HMAC签名)
- 管理员站点管理: 站点 CRUD
- API 代理: 多站点切换，会话管理

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/db.ts

@@ -0,0 +1,37 @@
+import Database from 'better-sqlite3'
+import path from 'path'
+import { fileURLToPath } from 'url'
+import fs from 'fs'
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+const DB_PATH = path.join(__dirname, '..', 'data', 'dashboard.db')
+
+fs.mkdirSync(path.dirname(DB_PATH), { recursive: true })
+
+const db = new Database(DB_PATH)
+db.pragma('journal_mode = WAL')
+db.pragma('foreign_keys = ON')
+
+db.exec(`
+  CREATE TABLE IF NOT EXISTS sites (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name TEXT NOT NULL,
+    url TEXT NOT NULL,
+    created_at TEXT DEFAULT (datetime('now')),
+    updated_at TEXT DEFAULT (datetime('now'))
+  );
+
+  CREATE TABLE IF NOT EXISTS sessions (
+    id TEXT PRIMARY KEY,
+    user_id INTEGER NOT NULL,
+    access_token TEXT NOT NULL,
+    site_id INTEGER NOT NULL,
+    site_url TEXT NOT NULL,
+    user_info TEXT DEFAULT '{}',
+    created_at TEXT DEFAULT (datetime('now')),
+    expires_at TEXT NOT NULL,
+    FOREIGN KEY (site_id) REFERENCES sites(id) ON DELETE CASCADE
+  );
+`)
+
+export default db