[ShawnChen-Sirius]

Update the three engine pins to v26.9.2-rc.2 to run the Rust CI matrix. This release candidate is for validation only; do not publish the crate against it.

Note

Test chdb-core v26.9.2-rc.2 in Rust CI and fix insert-options lifetime

• Pins the chDB engine to v26.9.2-rc.2 in Cargo.toml, build.rs, and update_libchdb.sh. This is a CI test pin; a stable engine must replace it before publishing.
• Fixes a lifetime bug in direct Arrow insertion: with_insert_options in connection.rs previously returned a pointer to a local C options struct that expired before the FFI call. It now runs the FFI call inside a callback while the options struct and settings string are still alive.
• Updates insert_arrow_array and insert_arrow_stream to use the new callback helper, and adds a test that options stay readable during the call.
• Compiles fallback-only state in arrow_insert.rs only when direct_arrow_insert is disabled.
• Risk: CHDB_ENGINE_PIN is a release candidate; do not publish without replacing it with a stable engine pin.

^{Macroscope summarized 1d4face.}

[ShawnChen-Sirius]

@wudidapaopao, please review this PR

[wudidapaopao]

LGTM