GPU decode silently skips extension-typed columns (date/timestamp)

[manish-sethi]

What happened?

It seems CudaArrayExt::execute_cuda (in vortex-cuda/src/executor.rs) treats every Extension array as already canonical and returns the host execution path, so extension-typed columns are never GPU-decoded — even though their storage (e.g., FoR → bitpacked) has working GPU kernels.

I guess this fits in item 4 of #8100

Steps to reproduce

• Scan a column whose dtype is an extension type over compressed storage — e.g. TPC-H l_shipdate column, encoded as vortex.ext(date[days]) → fastlanes.for → fastlanes.bitpacked
• The packed buffer is copied H2D, but no decode kernel launches

Environment

Vortex Commit - 126c431

Additional context

No response

[0ax1]

Looking into this!