Add generic AI job queue lifecycle

internal/model/job.go

@@ -32,6 +32,8 @@ type Job struct {
 	ScheduledAt    time.Time       `json:"scheduled_at"`
 	StartedAt      *time.Time      `json:"started_at,omitempty"`
 	CompletedAt    *time.Time      `json:"completed_at,omitempty"`
+	WorkerID       *string         `json:"worker_id,omitempty"`
+	HeartbeatAt    *time.Time      `json:"heartbeat_at,omitempty"`
 	CreatedAt      time.Time       `json:"created_at"`
 	UpdatedAt      time.Time       `json:"updated_at"`
 	IdempotencyKey *string         `json:"idempotency_key,omitempty"`
@@ -49,6 +51,22 @@ type CreateJob struct {
 	IdempotencyKey *string         `json:"idempotency_key,omitempty"`
 }
 
+type ClaimJobs struct {
+	WorkerID      string   `json:"worker_id"`
+	TaskTypes     []string `json:"task_types"`
+	ModelProfiles []string `json:"model_profiles"`
+	Limit         int      `json:"limit"`
+}
+
+type CompleteJob struct {
+	Result json.RawMessage `json:"result"`
+}
+
+type FailJob struct {
+	ErrorCode    string `json:"error_code"`
+	ErrorMessage string `json:"error_message"`
+}
+
 type QueueStat struct {
 	TaskType     string `json:"task_type"`
 	ModelProfile string `json:"model_profile"`