feat(api): 初始化笔记应用后端基础架构

- 添加环境配置文件 .env.example 包含数据库、JWT、CORS等配置
- 创建 .gitignore 文件忽略敏感文件和临时文件
- 配置 Apache 重写规则支持路由转发
- 实现 JWT 认证中间件提供用户身份验证功能
- 添加 MySQL 数据库初始化脚本包含分组、图片、笔记表结构

biji-php/src/Utils/Database.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace App\Utils;
+
+use PDO;
+use PDOException;
+
+class Database
+{
+    private static $instance = null;
+    private $connection;
+
+    private function __construct()
+    {
+        $config = require __DIR__ . '/../../config/database.php';
+
+        $dsn = sprintf(
+            "mysql:host=%s;port=%s;dbname=%s;charset=%s",
+            $config['host'],
+            $config['port'],
+            $config['database'],
+            $config['charset']
+        );
+
+        try {
+            $this->connection = new PDO(
+                $dsn,
+                $config['username'],
+                $config['password'],
+                $config['options']
+            );
+        } catch (PDOException $e) {
+            throw new \Exception("数据库连接失败: " . $e->getMessage());
+        }
+    }
+
+    public static function getInstance()
+    {
+        if (self::$instance === null) {
+            self::$instance = new self();
+        }
+        return self::$instance;
+    }
+
+    public function getConnection()
+    {
+        return $this->connection;
+    }
+}

biji-php/src/Utils/JWTUtil.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace App\Utils;
+
+use Firebase\JWT\JWT;
+use Firebase\JWT\Key;
+
+class JWTUtil
+{
+    private static $secret;
+    private static $expire;
+
+    public static function init()
+    {
+        self::$secret = $_ENV['JWT_SECRET'] ?? 'default-secret-key';
+        self::$expire = (int)($_ENV['JWT_EXPIRE'] ?? 86400);
+    }
+
+    public static function encode($userId, $username)
+    {
+        self::init();
+
+        $payload = [
+            'iss' => 'biji-php',
+            'iat' => time(),
+            'exp' => time() + self::$expire,
+            'userId' => $userId,
+            'username' => $username
+        ];
+
+        return JWT::encode($payload, self::$secret, 'HS256');
+    }
+
+    public static function decode($token)
+    {
+        self::init();
+
+        try {
+            $decoded = JWT::decode($token, new Key(self::$secret, 'HS256'));
+            return (array)$decoded;
+        } catch (\Exception $e) {
+            return null;
+        }
+    }
+}

biji-php/src/Utils/Response.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace App\Utils;
+
+class Response
+{
+    public static function success($data = null, $message = '操作成功')
+    {
+        return [
+            'code' => 200,
+            'message' => $message,
+            'data' => $data
+        ];
+    }
+
+    public static function fail($message = '操作失败', $code = 400)
+    {
+        return [
+            'code' => $code,
+            'message' => $message,
+            'data' => null
+        ];
+    }
+
+    public static function error($message = '服务器错误', $code = 500)
+    {
+        return [
+            'code' => $code,
+            'message' => $message,
+            'data' => null
+        ];
+    }
+
+    /**
+     * 将数组转换为 JSON 字符串（中文不转义）
+     */
+    public static function json($data)
+    {
+        return json_encode($data, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+    }
+}