initial commit: Go version of SMS Receiver with fixed template rendering

- Implemented all core features from Python version
- Fixed int64/int type compatibility in template functions
- Added login authentication, SMS receiving, statistics, logs
- Independent database: sms_receiver_go.db
- Fixed frontend display issues for message list and statistics

auth/auth.go

@@ -0,0 +1,129 @@
+package auth
+
+import (
+	"encoding/hex"
+	"log"
+	"net/http"
+	"time"
+
+	"sms-receiver-go/config"
+
+	"github.com/gorilla/sessions"
+)
+
+var store *sessions.CookieStore
+
+// SessionKey 会话相关的 key
+const (
+	SessionKeyLoggedIn   = "logged_in"
+	SessionKeyUsername   = "username"
+	SessionKeyLoginTime  = "login_time"
+	SessionKeyLastActive = "last_activity"
+)
+
+// Init 初始化会话存储
+func Init(secretKey string) {
+	// 支持 hex 和 base64 格式的密钥
+	key := []byte(secretKey)
+	if len(key) == 64 { // hex 格式 32 字节
+		var err error
+		key, err = hex.DecodeString(secretKey)
+		if err != nil {
+			log.Printf("警告: hex 解码失败，使用原始密钥: %v", err)
+		}
+	}
+
+	store = sessions.NewCookieStore(key)
+	store.Options = &sessions.Options{
+		Path:     "/",
+		MaxAge:   86400 * 7, // 7天
+		HttpOnly: true,
+		// 不设置 SameSite，让浏览器使用默认值（Lax），在同站上下文中工作正常
+		// SameSite: http.SameSiteNoneMode,
+		// Secure:   true,
+	}
+	log.Printf("会话存储初始化完成，密钥长度: %d 字节", len(key))
+}
+
+// GetStore 获取会话存储
+func GetStore() *sessions.CookieStore {
+	return store
+}
+
+// Login 登录
+func Login(w http.ResponseWriter, r *http.Request, username string) error {
+	session, err := store.Get(r, "sms-receiver")
+	if err != nil {
+		return err
+	}
+
+	session.Values[SessionKeyLoggedIn] = true
+	session.Values[SessionKeyUsername] = username
+	session.Values[SessionKeyLoginTime] = time.Now().Unix()
+	session.Values[SessionKeyLastActive] = time.Now().Unix()
+
+	return session.Save(r, w)
+}
+
+// Logout 登出
+func Logout(r *http.Request, w http.ResponseWriter) error {
+	session, err := store.Get(r, "sms-receiver")
+	if err != nil {
+		return err
+	}
+
+	session.Values = make(map[interface{}]interface{})
+	session.Save(r, w)
+	return nil
+}
+
+// IsLoggedIn 检查是否已登录
+func IsLoggedIn(r *http.Request) (bool, string) {
+	session, err := store.Get(r, "sms-receiver")
+	if err != nil {
+		return false, ""
+	}
+
+	loggedIn, ok := session.Values[SessionKeyLoggedIn].(bool)
+	if !ok || !loggedIn {
+		return false, ""
+	}
+
+	username, _ := session.Values[SessionKeyUsername].(string)
+
+	// 检查会话是否过期
+	cfg := config.Get()
+	if cfg != nil {
+		lastActive, ok := session.Values[SessionKeyLastActive].(int64)
+		if ok {
+			sessionLifetime := cfg.GetSessionLifetimeDuration()
+			if time.Now().Unix()-lastActive > int64(sessionLifetime.Seconds()) {
+				return false, ""
+			}
+			// 更新最后活跃时间
+			session.Values[SessionKeyLastActive] = time.Now().Unix()
+		}
+	}
+
+	return true, username
+}
+
+// CheckLogin 检查登录状态，未登录则跳转到登录页
+func CheckLogin(w http.ResponseWriter, r *http.Request) (bool, string) {
+	loggedIn, username := IsLoggedIn(r)
+	if !loggedIn {
+		http.Redirect(w, r, "/login", http.StatusSeeOther)
+		return false, ""
+	}
+	return true, username
+}
+
+// GetCurrentUser 获取当前用户名
+func GetCurrentUser(r *http.Request) string {
+	session, err := store.Get(r, "sms-receiver")
+	if err != nil {
+		return ""
+	}
+	username, _ := session.Values[SessionKeyUsername].(string)
+	return username
+}