Expose pooled CUDA file scans through FFI

[onursatici]

Rationale for this change

We don't expose a way in ffi to use the pinned buffer pool on reading vortex files into the GPU

What changes are included in this PR?

cuda session now owns the buffer pool, and that is shared on scans done with this context

[github-actions]

Polar Signals Profiling Results

Latest Run

Status	Commit	Job	Attempt	Link
🟢 Done	61345d8		1	Explore Profiling Data

Previous Runs (1)

Status	Commit	Job	Attempt	Link
🟢 Done	eb5b635		1	Explore Profiling Data

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[github-actions]

Benchmarks: Vortex queries

Verdict: No clear signal (low confidence)
Attributed Vortex impact: -0.6%
Engines: DataFusion No clear signal (+9.1%, low confidence) · DuckDB Likely improvement (-9.5%, medium confidence)
Vortex (geomean): 0.840x ✅
Parquet (geomean): 0.843x ✅
Shifts: Parquet (control) -15.7% · Median polish -16.2%

How to read Verdict and Engines

• Verdict: Overall PR-level signal after subtracting baseline drift estimated from Parquet control rows. It can be Likely improvement, Likely regression, or No clear signal.
• Engines: Per-engine attribution. DataFusion is compared against DataFusion/Parquet controls; DuckDB is compared against DuckDB/Parquet controls. This answers whether each engine improved or regressed independently.
• Confidence: Based on directional consistency, share of rows above the noise floor, and control-run noise.

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datafusion / vortex-file-compressed (0.857x ✅, 2↑ 0↓)

name	PR 61345d8 (ns)	base e727c46 (ns)	ratio (PR/base)
vortex_q00/datafusion:vortex-file-compressed 🚀	10052101	11634784	0.86
vortex_q01/datafusion:vortex-file-compressed 🚀	6556625	7718973	0.85

datafusion / parquet (0.785x ✅, 2↑ 0↓)

name	PR 61345d8 (ns)	base e727c46 (ns)	ratio (PR/base)
vortex_q00/datafusion:parquet 🚀	20602447	25949078	0.79
vortex_q01/datafusion:parquet 🚀	4727027	6089901	0.78

duckdb / vortex-file-compressed (0.819x ✅, 2↑ 0↓)

name	PR 61345d8 (ns)	base e727c46 (ns)	ratio (PR/base)
vortex_q00/duckdb:vortex-file-compressed 🚀	10053260	12065527	0.83
vortex_q01/duckdb:vortex-file-compressed 🚀	5954243	7392324	0.81

duckdb / parquet (0.905x ➖, 1↑ 0↓)

name	PR 61345d8 (ns)	base e727c46 (ns)	ratio (PR/base)
vortex_q00/duckdb:parquet 🚀	23546974	26698649	0.88
vortex_q01/duckdb:parquet	9362288	10071331	0.93

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No file size changes detected.