feat: 대시보드 내 이슈(/my/tasks) + 전체 캘린더(CalendarEvent) + 메일 AI 요약(OpenAI)

- GET /my/tasks: 전 프로젝트에서 나에게 배정된 작업 + projectName (대시보드 JIRA 보드용)
  · fix: ORDER BY "end"(예약어) 따옴표 처리
- CalendarEvent 모델 + /calendar/events CRUD(본인 소유), nav에 캘린더 추가
- internal/ai(OpenAI, stdlib): 메일 동기화 시 신규 메일에 한 줄 AI 요약 생성(OPENAI_API_KEY)
  · ProjectMailMsg.Summary, 회당 40건 상한
- nav inbox 라벨 쪽지함으로 통일

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/models/models.go

@@ -29,7 +29,7 @@ func All() []interface{} {
 		// slice 3 — projects
 		&Company{}, &Product{}, &Version{}, &Project{}, &ProjectMember{},
 		&ClientContact{}, &ProjectTask{}, &TaskComment{}, &MailNote{}, &ProjectMailMsg{}, &ProjectMailState{},
-		&Contract{}, &ContractFile{}, &PaymentSplit{},
+		&CalendarEvent{}, &Contract{}, &ContractFile{}, &PaymentSplit{},
 		// slice 4 — incentive
 		&IncentiveConfig{}, &PaymentStage{}, &UserIncentive{}, &QuarterlySettlement{},
 		// slice 5 — accounting

internal/models/project.go

@@ -152,6 +152,7 @@ type ProjectMailMsg struct {
 	CcAddr    string    `json:"cc"`
 	Subject   string    `json:"subject"`
 	Snippet   string    `json:"snippet"`
+	Summary   string    `json:"summary"` // AI 자동 요약(한 줄)
 	DateHdr   string    `json:"date"`
 	Mailbox   string    `json:"mailbox"`
 	TS        int64     `gorm:"index" json:"ts"`
@@ -171,6 +172,25 @@ type ProjectMailState struct {
 	Count        int        `json:"count"`
 }
 
+// CalendarEvent is a personal calendar entry tagged by category(프로젝트/기타/개인)
+// with a color. Owned by one member.
+type CalendarEvent struct {
+	Base
+	OwnerEmail string    `gorm:"index" json:"ownerEmail"`
+	Title      string    `json:"title"`
+	Category   string    `json:"category"`  // project | etc | personal (분류 키)
+	ProjectID  string    `json:"projectId"` // category=project일 때 연결
+	Color      string    `json:"color"`     // 표시 색
+	Start      string    `json:"start"`     // YYYY-MM-DD
+	End        string    `json:"end"`       // YYYY-MM-DD (빈값=하루)
+	AllDay     bool      `json:"allDay"`
+	Memo       string    `json:"memo"`
+	CreatedAt  time.Time `json:"createdAt"`
+	UpdatedAt  time.Time `json:"updatedAt"`
+}
+
+func (m *CalendarEvent) BeforeCreate(*gorm.DB) error { m.ensureID(); return nil }
+
 // Contract holds the [admin-only] commercial terms of a project. BE is the
 // break-even floor (손해가 안 나는 최소 금액). Exposed ONLY to admins.
 type Contract struct {