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

models/message.go

@@ -0,0 +1,67 @@
+package models
+
+import (
+	"database/sql"
+	"time"
+)
+
+// SMSMessage 短信消息模型
+type SMSMessage struct {
+	ID                int64          `json:"id"`
+	FromNumber        string         `json:"from_number"`
+	Content           string         `json:"content"`
+	Timestamp         int64          `json:"timestamp"`
+	TimestampStr      string         `json:"timestamp_str,omitempty"`      // 显示用
+	LocalTimestampStr string         `json:"local_timestamp_str,omitempty"` // 显示用
+	DeviceInfo        sql.NullString `json:"device_info,omitempty"`
+	SIMInfo           sql.NullString `json:"sim_info,omitempty"`
+	SignVerified      sql.NullBool   `json:"sign_verified,omitempty"`
+	IPAddress         string         `json:"ip_address"`
+	CreatedAt         time.Time      `json:"created_at"`
+}
+
+// ReceiveLog 接收日志模型
+type ReceiveLog struct {
+	ID            int64          `json:"id"`
+	FromNumber    string         `json:"from_number"`
+	Content       string         `json:"content"`
+	Timestamp     int64          `json:"timestamp"`
+	Sign          sql.NullString `json:"sign,omitempty"`
+	SignValid     sql.NullBool   `json:"sign_valid,omitempty"`
+	IPAddress     string         `json:"ip_address"`
+	Status        string         `json:"status"`
+	ErrorMessage  sql.NullString `json:"error_message,omitempty"`
+	CreatedAt     time.Time      `json:"created_at"`
+}
+
+// Statistics 统计信息
+type Statistics struct {
+	Total      int64 `json:"total"`
+	Today      int64 `json:"today"`
+	Week       int64 `json:"week"`
+	Verified   int64 `json:"verified"`
+	Unverified int64 `json:"unverified"`
+}
+
+// MessageListResponse 消息列表响应
+type MessageListResponse struct {
+	Success bool        `json:"success"`
+	Data    []SMSMessage `json:"data"`
+	Total   int64       `json:"total"`
+	Page    int         `json:"page"`
+	Limit   int         `json:"limit"`
+}
+
+// StatisticsResponse 统计响应
+type StatisticsResponse struct {
+	Success bool       `json:"success"`
+	Data    Statistics `json:"data"`
+}
+
+// APIResponse API 通用响应
+type APIResponse struct {
+	Success   bool   `json:"success"`
+	Message   string `json:"message,omitempty"`
+	MessageID int64  `json:"message_id,omitempty"`
+	Error     string `json:"error,omitempty"`
+}