feat(phase2e-2): Go meeting 模块 DDL + Model + DAO + service/controller/router 骨架（Task 3+4）

Task 3 - 数据库与持久化层：
- init.sql 追加 3 张表（meeting_rooms / meeting_participants / meeting_chats）+ 9 索引 + 全量 COMMENT
- 新增 phase2e2_migration.sql 增量升级脚本（IF NOT EXISTS 幂等）
- app/constants/meeting.go 统一会议常量（类型/状态/角色/结束原因/离会原因/默认配置/WS 事件 8 组）
- app/meeting/model 3 个 model + GORM tag（TIMESTAMP(0) 对齐现有表风格）
- app/meeting/dao 3 个 DAO 共 24 个方法：
  * meeting_room_dao：Create/Get/Exists/MarkStarted/MarkEnded（乐观锁）/UpdateHost/UpdateSettings/ListByHost/ListExpiredForCleanup
  * meeting_participant_dao：JoinRoom（事务内复用旧记录）/LeaveRoom（EXTRACT(EPOCH) DB 时间）/LeaveAllActive/TransferHost（事务）/FindActiveByUser（JOIN 单点校验）/列表计数更新
  * meeting_chat_dao：Create/ListByRoom（游标）/DeleteByRoomIDs/CountByRoom
- psql 真库跑通 CRUD + UNIQUE + CASCADE + 主持人转让事务 + duration=10s 精确匹配 8 场景

Task 4 - Go 侧 service/controller/router/wire 骨架：
- app/meeting/service/interfaces.go：NotifyPusher / UserInfoResolver / OnlineChecker 三接口（解耦 notify/contact/ws）
- app/meeting/service/meeting_service.go：MeetingService + 8 sentinel error + 17 个空方法（返回 ErrNotImplemented）
- app/meeting/controller/meeting_controller.go：12 个 Gin handler + responseNotImplemented（501）
- app/meeting/router.go：12 条路由挂 /api/v1/meeting/* 并套 jwtAuth（扁平化 router.go，与 group/notify 一致）
- app/meeting/provider.go：MeetingSet = wire.NewSet(DAO×3, Service, Controller)
- 全局 wire.go 挂入 MeetingSet + 3 条 wire.Bind（Notify/UserInfo/Online）；App struct/NewApp 加字段；router/router.go 挂载
- 存量修复：admin/provider.go 补齐 MessageManage{DAO,Service,Controller} 解决旧版 wire 重生成报 no provider found
- 验证：go build ./... / go vet ./... / wire ./app/provider 零错误；GIN_MODE=debug 启动打印全部 12 条路由；无 token curl 3 条代表性路由均返回 401（JWT 中间件生效）

关键风格修正（偏离草案）：
- 常量归入 app/constants/meeting.go 单文件（与 group.go / notify.go 同构），非草案 app/meeting/constants/
- TIMESTAMP(0) 取代草案 TIMESTAMPTZ 对齐所有现有表
- 冗余 idx_meeting_rooms_code 移除（UNIQUE 已自动建索引）
- router/provider 目录扁平化（app/meeting/router.go / app/meeting/provider.go）
- 延续项目 Go 侧"零 _test.go"风格，用代码审查 + psql 真库验证 + Playwright E2E 三层守护

文档同步：
- docs/progress/CURRENT_STATUS.md 新增 Task 3 / Task 4 交付段落
- .cursor/rules/project-context.mdc Phase 2e-2 进度推进至 Task 0-4 ✅
- docs/plans/2026-04-21-phase2e-2-implementation.plan.md Task 3 / Task 4 标记完成 + 实际产出 vs 计划差异

Made-with: Cursor

backend/go-service/app/meeting/controller/meeting_controller.go

@@ -0,0 +1,138 @@
+// Package controller 提供 meeting 模块的 HTTP 接口
+package controller
+
+import (
+	"net/http"
+
+	"github.com/echochat/backend/app/meeting/service"
+	"github.com/echochat/backend/pkg/middleware"
+	"github.com/echochat/backend/pkg/utils"
+	"github.com/gin-gonic/gin"
+)
+
+// MeetingController 会议 REST 控制器
+// Task 4 骨架阶段：所有 handler 均返回 501 Not Implemented，便于路由自测与前端 mock
+// Task 5/6/7 将在此填充请求解析、业务调用与错误映射
+type MeetingController struct {
+	meetingService *service.MeetingService
+}
+
+// NewMeetingController 创建 MeetingController 实例
+func NewMeetingController(meetingService *service.MeetingService) *MeetingController {
+	return &MeetingController{meetingService: meetingService}
+}
+
+// responseNotImplemented Task 4 占位响应，Task 5/6/7 逐接口替换为真实实现
+func responseNotImplemented(c *gin.Context, endpoint string) {
+	c.JSON(http.StatusNotImplemented, gin.H{
+		"code":     http.StatusNotImplemented,
+		"message":  "接口尚未实现",
+		"endpoint": endpoint,
+	})
+}
+
+// requireUserID 统一的当前用户取值，失败直接写 401 并返回 false
+func requireUserID(c *gin.Context) (int64, bool) {
+	userID, ok := middleware.GetCurrentUserID(c)
+	if !ok {
+		utils.ResponseUnauthorized(c, "无法获取当前用户信息")
+		return 0, false
+	}
+	return userID, true
+}
+
+// CreateRoom POST /api/v1/meeting/rooms
+func (ctl *MeetingController) CreateRoom(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms")
+}
+
+// GetRoom GET /api/v1/meeting/rooms/:code
+func (ctl *MeetingController) GetRoom(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "GET /api/v1/meeting/rooms/:code")
+}
+
+// JoinRoom POST /api/v1/meeting/rooms/:code/join
+func (ctl *MeetingController) JoinRoom(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms/:code/join")
+}
+
+// LeaveRoom POST /api/v1/meeting/rooms/:code/leave
+func (ctl *MeetingController) LeaveRoom(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms/:code/leave")
+}
+
+// EndRoom POST /api/v1/meeting/rooms/:code/end
+func (ctl *MeetingController) EndRoom(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms/:code/end")
+}
+
+// ListMyMeetings GET /api/v1/meeting/rooms?role=host|participant
+func (ctl *MeetingController) ListMyMeetings(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "GET /api/v1/meeting/rooms")
+}
+
+// TransferHost POST /api/v1/meeting/rooms/:code/transfer-host
+func (ctl *MeetingController) TransferHost(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms/:code/transfer-host")
+}
+
+// KickMember POST /api/v1/meeting/rooms/:code/kick
+func (ctl *MeetingController) KickMember(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms/:code/kick")
+}
+
+// InviteUsers POST /api/v1/meeting/rooms/:code/invite
+func (ctl *MeetingController) InviteUsers(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms/:code/invite")
+}
+
+// RedeemInvite POST /api/v1/meeting/invites/:token/redeem
+func (ctl *MeetingController) RedeemInvite(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/invites/:token/redeem")
+}
+
+// SendChat POST /api/v1/meeting/rooms/:code/chats
+func (ctl *MeetingController) SendChat(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "POST /api/v1/meeting/rooms/:code/chats")
+}
+
+// ListChats GET /api/v1/meeting/rooms/:code/chats?after_id=&limit=
+func (ctl *MeetingController) ListChats(c *gin.Context) {
+	if _, ok := requireUserID(c); !ok {
+		return
+	}
+	responseNotImplemented(c, "GET /api/v1/meeting/rooms/:code/chats")
+}