feat(clickhouse): [WRA-9] add configurable stream_buffer_size option to ClickHouse FDW

[burmecia]

What kind of change does this PR introduce?

This PR is add a configurable stream_buffer_size option to ClickHouse FDW.

What is the current behavior?

The stream buffer size is hard coded to 1024.

What is the new behavior?

• Add stream_buffer_size option to allow users to configure the internal streaming buffer size
• Implement validation to enforce limits between 1 and 100000 rows
• Values outside the valid range are automatically clamped to nearest bound
• Update documentation to reflect new option and its limits
• Default value remains 1024 rows for backward compatibility

Additional context

N/A

[Copilot]

Pull Request Overview

This PR adds a configurable stream_buffer_size option to the ClickHouse FDW, allowing users to tune the internal buffer size for streaming data. The version is bumped from 0.1.8 to 0.1.9.

• Added stream_buffer_size foreign table option with validation (clamped between 1 and 100,000, defaults to 1024)
• Reorganized documentation to group all foreign table options together
• Updated changelog and documentation

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
wrappers/src/fdw/clickhouse_fdw/clickhouse_fdw.rs	Bumped version to 0.1.9 and implemented stream_buffer_size option parsing with validation
wrappers/src/fdw/clickhouse_fdw/tests.rs	Added stream_buffer_size option to test table definition
wrappers/src/fdw/clickhouse_fdw/README.md	Added changelog entry for version 0.1.9
docs/catalog/clickhouse.md	Documented stream_buffer_size option and reorganized foreign table options section

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