Add scheduler batch size option

[yang-xiaodong]

Summary

• add SchedulerBatchSize option to limit scheduler fetch size
• support the new limit in PostgreSql, MySql, SqlServer, MongoDB, and InMemory storages
• document SchedulerBatchSize in both English and Chinese configuration docs

Testing

• dotnet test --no-restore --verbosity minimal (fails: command not found)

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https://chatgpt.com/codex/tasks/task_e_68500d907df88320972e9759b7612750