remove alignedslice and replace with direct poly calls

[JordanMaples]

I synced up with @hildebrandmw after he returned from vacation and learned that I misunderstood the brief of #907 with my #965 pr. Rather than removing the struct and replace it with a type-alias for slightly less overhead, the ask was to just replace all calls. So, this follow-up PR does just that and removes AlignedSlice & aligned_slice and replaces all sites with Poly::broadcast calls.

This also introduces PowerOfTwo consts for 0..64 P and value mappings and AlignedAllocator consts for 4...4096

[Copilot]

Pull request overview

This PR completes the follow-up to #907 by removing the AlignedSlice/aligned_slice abstraction and migrating call sites to use Poly::broadcast directly, while also adding pre-defined alignment/power-of-two constants to simplify common allocations.

Changes:

• Remove AlignedSlice type alias and aligned_slice() constructor from diskann-quantization::alloc and update all call sites to use Poly::broadcast.
• Add PowerOfTwo consts (P0..P63 + value-mapped V*) and AlignedAllocator consts (A4..A4096) for common alignments.
• Drop unused workspace dependency (once_cell).

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
diskann-quantization/src/num.rs	Adds many PowerOfTwo constants (P*/V*) to avoid repeated runtime construction.
diskann-quantization/src/alloc/mod.rs	Stops exporting AlignedSlice/aligned_slice from the public alloc module API.
diskann-quantization/src/alloc/aligned_slice.rs	Deletes the alias + constructor and the associated tests.
diskann-quantization/src/alloc/aligned.rs	Adds AlignedAllocator::{A4..A4096} convenience constants.
diskann-disk/src/utils/aligned_file_reader/windows_aligned_file_reader.rs	Updates tests to allocate aligned buffers via Poly::broadcast + AlignedAllocator.
diskann-disk/src/utils/aligned_file_reader/storage_provider_aligned_file_reader.rs	Same as above for storage-provider aligned reader tests.
diskann-disk/src/utils/aligned_file_reader/linux_aligned_file_reader.rs	Same as above for Linux aligned reader tests.
diskann-disk/src/search/provider/disk_vertex_provider_factory.rs	Switches header read buffer allocation to Poly::broadcast.
diskann-disk/src/search/provider/disk_sector_graph.rs	Replaces AlignedSlice<u8> storage with Poly<[u8], AlignedAllocator> and allocates via Poly::broadcast.
diskann-disk/src/search/pq/pq_scratch.rs	Replaces aligned scratch buffers with Poly::broadcast allocations.
diskann-disk/benches/benchmarks_iai/aligned_file_reader_bench_iai.rs	Updates benchmark allocations to Poly::broadcast.
diskann-disk/benches/benchmarks/aligned_file_reader_bench.rs	Updates benchmark allocations to Poly::broadcast.
Cargo.toml	Removes once_cell from workspace dependencies.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.42%. Comparing base (cb52a9f) to head (4a2b598).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #994      +/-   ##
==========================================
- Coverage   89.43%   89.42%   -0.01%     
==========================================
  Files         449      448       -1     
  Lines       83779    83743      -36     
==========================================
- Hits        74928    74890      -38     
- Misses       8851     8853       +2     

Flag	Coverage Δ
miri	89.42% <100.00%> (-0.01%)	⬇️
unittests	89.26% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
diskann-disk/src/search/pq/pq_scratch.rs	79.54% <100.00%> (ø)
...kann-disk/src/search/provider/disk_sector_graph.rs	96.96% <100.00%> (+0.02%)	⬆️
...rc/search/provider/disk_vertex_provider_factory.rs	95.70% <100.00%> (ø)
...s/aligned_file_reader/linux_aligned_file_reader.rs	82.65% <100.00%> (ø)
...ile_reader/storage_provider_aligned_file_reader.rs	98.36% <100.00%> (ø)
diskann-quantization/src/alloc/aligned.rs	97.82% <ø> (ø)
diskann-quantization/src/alloc/mod.rs	100.00% <ø> (ø)
diskann-quantization/src/num.rs	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

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[JordanMaples]

@copilot could you review again? I believe that I've fully addressed your comments

[Copilot]

@copilot could you review again? I believe that I've fully addressed your comments

All five issues from the previous review have been addressed in commit afa3f89:

• Error propagation (no more .unwrap()) in DiskSectorGraph::new, reconfigure, PQScratch::new, and get_header — all now use .map_err(ANNError::log_index_error)?
• PowerOfTwo constants P32–P63 (and their V* aliases) are gated behind #[cfg(target_pointer_width = "64")] to prevent compile-time overflow on 32-bit targets

Clippy and tests pass cleanly.