feat(schedule): enhance schedule tasks with web search and batch generation support

Add enable_web_search and generate_count columns to schedule_tasks table.
Refactor schedule task service to publish generation jobs to RabbitMQ
instead of inline execution, supporting batch dispatch and backpressure
awareness via scheduler process.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/internal/tenant/domain/schedule_task.go

@@ -3,17 +3,20 @@ package domain
 import "time"
 
 type ScheduleTask struct {
-	ID             int64
-	TenantID       int64
-	PromptRuleID   int64
-	BrandID        *int64
-	Name           string
-	CronExpr       string
-	TargetPlatform *string
-	StartAt        *time.Time
-	EndAt          *time.Time
-	NextRunAt      *time.Time
-	Status         string
-	CreatedAt      time.Time
-	UpdatedAt      time.Time
+	ID              int64
+	TenantID        int64
+	OperatorID      *int64
+	PromptRuleID    int64
+	BrandID         *int64
+	Name            string
+	CronExpr        string
+	TargetPlatform  *string
+	EnableWebSearch bool
+	GenerateCount   int
+	StartAt         *time.Time
+	EndAt           *time.Time
+	NextRunAt       *time.Time
+	Status          string
+	CreatedAt       time.Time
+	UpdatedAt       time.Time
 }