feat: 核心电费查询 Go 服务

- FasterLZU 登录 + xiaofubao 6 步电费链路

- shiroJID 会话缓存 + 每日记录存储

- 定时任务: 每天 00:00 记录, 失败重试 5 次

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

go/crypto.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/md5"
+	"encoding/hex"
+	"fmt"
+	"strings"
+)
+
+// crypto.go - AES-CBC 加密/解密 + MD5 签名（与 FasterLZU APP 行为一致）
+// 密钥必须通过环境变量 LZU_AES_KEY / LZU_MD5_KEY 提供（16 字节）
+
+var (
+	aesKey = envOr("LZU_AES_KEY", "") // 16 字节，由部署环境注入
+	md5Key = envOr("LZU_MD5_KEY", "")
+)
+
+// aesEncrypt 使用 AES-CBC，IV=key，零填充，输出小写 hex
+func aesEncrypt(plaintext string) (string, error) {
+	key := []byte(aesKey)
+	if len(key) != 16 {
+		return "", fmt.Errorf("AES key 长度不是 16 字节")
+	}
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", err
+	}
+	data := []byte(plaintext)
+	// 零填充到 blockSize 的整数倍
+	blockSize := aes.BlockSize
+	paddedLen := len(data)
+	if paddedLen%blockSize != 0 {
+		paddedLen = len(data) + (blockSize - len(data)%blockSize)
+	}
+	padded := make([]byte, paddedLen)
+	copy(padded, data)
+	// 剩余部分保持 0x00（零填充）
+
+	iv := key
+	mode := cipher.NewCBCEncrypter(block, iv)
+	ciphertext := make([]byte, paddedLen)
+	mode.CryptBlocks(ciphertext, padded)
+	return hex.EncodeToString(ciphertext), nil
+}
+
+// aesDecrypt AES-CBC 解密，去除尾部零填充
+func aesDecrypt(hexStr string) (string, error) {
+	key := []byte(aesKey)
+	if len(key) != 16 {
+		return "", fmt.Errorf("AES key 长度不是 16 字节")
+	}
+	encrypted, err := hex.DecodeString(hexStr)
+	if err != nil {
+		return "", err
+	}
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", err
+	}
+	iv := key
+	mode := cipher.NewCBCDecrypter(block, iv)
+	decrypted := make([]byte, len(encrypted))
+	mode.CryptBlocks(decrypted, encrypted)
+	// 去除尾部零填充
+	validLen := len(decrypted)
+	for i := len(decrypted) - 1; i >= 0 && i >= len(decrypted)-16; i-- {
+		if decrypted[i] != 0 {
+			break
+		}
+		validLen--
+	}
+	return string(decrypted[:validLen]), nil
+}
+
+// md5Encrypt 签名: 参数值以 | 连接，末尾拼接 key，返回 MD5 hex
+func md5Encrypt(params []string, key string) string {
+	data := strings.Join(params, "|") + "|" + key
+	sum := md5.Sum([]byte(data))
+	return hex.EncodeToString(sum[:])
+}