refactor(array): use buffer allocator in execution context

[gatesn]

Summary

Add a buffer allocator to execution and I/O contexts.

Changes

• Store BufferAllocatorRef in ExecutionContext.
• Use it for chunked canonicalization.
• Allocate file and object-store reads with the caller allocator.
• Remove the old array memory allocator wrapper.

[codspeed-hq]

Merging this PR will degrade performance by 3.01%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 2 regressed benchmarks
✅ 2154 untouched benchmarks
⏩ 106 skipped benchmarks¹
🗄️ 4 archived benchmarks run²

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	cast_i32_to_u32[8192]	340.4 µs	416.4 µs	-18.23%
❌	WallTime	deferred_i64_avx2[PerRowPerRow]	10 µs	11.1 µs	-10.32%
⚡	Simulation	new_raw_prim_test_between[i32, 2048]	77.3 µs	62.1 µs	+24.43%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing ngates/buffer-allocator-context (884d9d1) with ngates/buffer-allocator-core (4911c36)³}

Footnotes

1. 106 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. 4 benchmarks were run, but are now archived. If they were deleted in another branch, consider rebasing to remove them from the report. Instead if they were added back, click here to restore them. ↩

3. No successful run was found on ngates/buffer-allocator-core (94c47cb) during the generation of this report, so 28b9baa was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩