Add lambda expressions

[mhk197]

Summary

• add lambda syntax with parameter validation, display-tree integration, traversal boundaries, and protobuf round-tripping
• add bound lambdas with signature dtypes, lexical parameter references, and capture tracking
• reject detached lambda or variable execution and optimization outside a higher-order function

Testing

• cargo +nightly fmt --all
• cargo clippy --all-targets --all-features
• cargo nextest run -p vortex-array (3460 passed, 1 skipped)
• cargo test --doc -p vortex-array
• git diff --check

[codspeed-hq]

Merging this PR will degrade performance by 4.63%

⚠️ 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
✅ 2087 untouched benchmarks
⏩ 206 skipped benchmarks¹
🗄️ 4 archived benchmarks run²

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	WallTime	arrow_checked_add_u32_avx512[16384]	17.6 µs	21.3 µs	-17.17%
❌	Simulation	cold_misaligned[(16, 64)]	344.2 µs	396 µs	-13.07%
⚡	WallTime	arrow_checked_add_u32_avx2[16384]	21.3 µs	17.7 µs	+20.48%

Tip

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

---

_{Comparing mk/lambda-expressions (d8e744f) with mk/variable-expressions (91f7aa1)}

Footnotes

1. 206 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. ↩