feat(websocket): integrate WebSocket support and refactor SSE handling

- Added WebSocket support by introducing a new WSHandler and related infrastructure.
- Replaced SSE implementations with WebSocket equivalents across message and QR code handlers.
- Updated service and repository layers to utilize WebSocket for real-time messaging.
- Removed obsolete SSE hub and related code, streamlining the application for WebSocket usage.
- Enhanced router to include WebSocket endpoints for real-time communication.

internal/model/call.go

@@ -0,0 +1,113 @@
+package model
+
+import (
+	"strconv"
+	"time"
+
+	"gorm.io/gorm"
+
+	"carrot_bbs/internal/pkg/utils"
+)
+
+// CallType 通话类型
+type CallType string
+
+const (
+	CallTypePrivate CallType = "private" // 私聊通话
+	CallTypeGroup   CallType = "group"   // 群聊通话
+)
+
+// CallStatus 通话状态
+type CallStatus string
+
+const (
+	CallStatusCalling   CallStatus = "calling"   // 呼叫中
+	CallStatusConnected CallStatus = "connected" // 已接通
+	CallStatusEnded     CallStatus = "ended"     // 已结束
+	CallStatusRejected  CallStatus = "rejected" // 已拒绝
+	CallStatusMissed    CallStatus = "missed"    // 未接听
+	CallStatusCancelled CallStatus = "cancelled" // 已取消
+)
+
+// ParticipantStatus 参与者状态
+type ParticipantStatus string
+
+const (
+	ParticipantStatusInvited  ParticipantStatus = "invited"  // 已邀请
+	ParticipantStatusJoined   ParticipantStatus = "joined"   // 已加入
+	ParticipantStatusLeft     ParticipantStatus = "left"     // 已离开
+	ParticipantStatusRejected ParticipantStatus = "rejected" // 已拒绝
+)
+
+// CallSession 通话会话
+type CallSession struct {
+	ID             string      `gorm:"primaryKey;size:20" json:"id"`                                          // 雪花算法ID
+	ConversationID string      `gorm:"not null;size:20;index" json:"conversation_id"`                         // 会话ID
+	GroupID        *string     `gorm:"index" json:"group_id,omitempty"`                                       // 群组ID（群聊时使用）
+	CallerID       string      `gorm:"column:caller_id;type:varchar(50);index;not null" json:"caller_id"`     // 发起者ID
+	CallType       CallType    `gorm:"type:varchar(20);not null" json:"call_type"`                            // 通话类型
+	Status         CallStatus  `gorm:"type:varchar(20);default:'calling'" json:"status"`                      // 通话状态
+	StartedAt      *time.Time  `json:"started_at,omitempty"`                                                  // 接通时间
+	EndedAt        *time.Time  `json:"ended_at,omitempty"`                                                    // 结束时间
+	Duration       int64       `gorm:"default:0" json:"duration"`                                             // 通话时长（秒）
+	CreatedAt      time.Time   `json:"created_at" gorm:"autoCreateTime"`
+	UpdatedAt      time.Time   `json:"updated_at" gorm:"autoUpdateTime"`
+	DeletedAt      gorm.DeletedAt `json:"-" gorm:"index"`
+
+	// 关联
+	Participants []CallParticipant `gorm:"foreignKey:CallID" json:"participants,omitempty"`
+}
+
+// BeforeCreate 创建前生成雪花算法ID
+func (c *CallSession) BeforeCreate(tx *gorm.DB) error {
+	if c.ID == "" {
+		id, err := utils.GetSnowflake().GenerateID()
+		if err != nil {
+			return err
+		}
+		c.ID = strconv.FormatInt(id, 10)
+	}
+	return nil
+}
+
+func (CallSession) TableName() string {
+	return "call_sessions"
+}
+
+// CallParticipant 通话参与者
+type CallParticipant struct {
+	ID        uint             `gorm:"primaryKey" json:"id"`
+	CallID    string           `gorm:"not null;size:20;index" json:"call_id"`                                 // 通话ID
+	UserID    string           `gorm:"column:user_id;type:varchar(50);index;not null" json:"user_id"`         // 用户ID
+	Status    ParticipantStatus `gorm:"type:varchar(20);default:'invited'" json:"status"`                     // 参与状态
+	JoinedAt  *time.Time       `json:"joined_at,omitempty"`                                                   // 加入时间
+	LeftAt    *time.Time       `json:"left_at,omitempty"`                                                     // 离开时间
+	CreatedAt time.Time        `json:"created_at" gorm:"autoCreateTime"`
+	UpdatedAt time.Time        `json:"updated_at" gorm:"autoUpdateTime"`
+}
+
+func (CallParticipant) TableName() string {
+	return "call_participants"
+}
+
+// IsPrivate 是否私聊通话
+func (c *CallSession) IsPrivate() bool {
+	return c.CallType == CallTypePrivate
+}
+
+// IsGroup 是否群聊通话
+func (c *CallSession) IsGroup() bool {
+	return c.CallType == CallTypeGroup
+}
+
+// IsActive 是否活跃通话
+func (c *CallSession) IsActive() bool {
+	return c.Status == CallStatusCalling || c.Status == CallStatusConnected
+}
+
+// CalculateDuration 计算通话时长
+func (c *CallSession) CalculateDuration() {
+	if c.StartedAt != nil && c.EndedAt != nil {
+		c.Duration = int64(c.EndedAt.Sub(*c.StartedAt).Seconds())
+	}
+}