fix(db): 重编号 Pages 部署源迁移避免版本冲突

main 已占用 202607190001（OpenResty 默认限流），
将 Pages source runtime / scanner seed 顺延为
202607190002、202607190003，并同步迁移测试期望配置数。

internal/db/migrator/pages_source_migration_test.go

@@ -21,8 +21,8 @@ import (
 )
 
 const (
-	pagesSourcePreviousMigration = int64(202607180001)
-	pagesSourceMigration         = int64(202607190001)
+	pagesSourcePreviousMigration = int64(202607190001)
+	pagesSourceMigration         = int64(202607190002)
 	pagesMigrationProjectID      = uint(900001)
 	pagesMigrationDeploymentID   = uint(900001)
 )