feat(vortex-geo): add native Hilbert scalar function

[HarukiMoriarty]

Summary

• move existing spatial scalar function IDs from vortex.geo.* to vortex.st.* while retaining vortex.geo.hilbert for the reusable native kernel
• add a fused vortex.geo.hilbert(geometry) to u32 scalar kernel over native GeoArrow storage
• calculate envelope centers without materializing a box column or decoding WKB
• treat nulls, empty list-backed geometries, and GeoArrow POINT EMPTY (NaN, NaN) as null keys

[codspeed-hq]

Merging this PR will improve performance by 14.81%

⚡ 3 improved benchmarks
✅ 1839 untouched benchmarks
⏩ 44 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	new_raw_prim_test_between[i32, 2048]	89.7 µs	76.7 µs	+16.92%
⚡	Simulation	execute_scalar_struct_simple	1.2 ms	1.1 ms	+14.34%
⚡	Simulation	execute_scalar_struct_wide	5.7 ms	5 ms	+13.2%

Tip

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_{Comparing nemo/geo-st-namespace (81828dc) with develop (fd43ebd)²}

Footnotes

1. 44 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. No successful run was found on develop (bc9aa10) during the generation of this report, so fd43ebd was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩