Remove AlignedBoxWithSlice wrapper and add alias to Poly<[T], AlignedAllocator>

[JordanMaples]

Closes #907

This change introduces AlignedSlice<T> type alias and the aligned_slice() constructor in diskann-quantization::alloc, replacing the AlignedBoxWithSlice wrapper struct from diskann-providers. This eliminates an unnecessary abstraction layer and moves aligned allocation to its proper tier.

• Add AlignedSlice<T> = Poly<[T], AlignedAllocator> type alias
• Add aligned_slice<T>(capacity, alignment) constructor
• Migrate all 9 consumer files in diskann-disk
• Replace split_into_nonoverlapping_mut_slices with chunks_mut
• Replace as_slice/as_mut_slice with Deref/DerefMut
• Delete aligned_allocator.rs from diskann-providers
• Add 5 tests for aligned_slice

[JordanMaples]

This replaces #908

[Copilot]

Pull request overview

This PR removes the AlignedBoxWithSlice wrapper from diskann-providers and standardizes aligned slice allocation in diskann-quantization::alloc via a new AlignedSlice<T> alias and aligned_slice() constructor, updating disk-index readers/search code to use the new API.

Changes:

• Add AlignedSlice<T> = Poly<[T], AlignedAllocator> and aligned_slice<T>(capacity, alignment: PowerOfTwo) in diskann-quantization.
• Migrate aligned buffer usage across diskann-disk (tests/benches/search) to the new constructor and to slice deref semantics.
• Remove diskann-providers::common::AlignedBoxWithSlice and replace custom splitting with chunks_mut.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
diskann-quantization/src/alloc/mod.rs	Exposes new aligned-slice module + re-exports AlignedSlice/aligned_slice.
diskann-quantization/src/alloc/aligned_slice.rs	Introduces AlignedSlice<T> alias, constructor, and unit tests.
diskann-providers/src/common/mod.rs	Drops AlignedBoxWithSlice re-export.
diskann-providers/src/common/aligned_allocator.rs	Deletes the wrapper implementation (and its tests).
diskann-disk/src/utils/aligned_file_reader/windows_aligned_file_reader.rs	Updates tests to allocate aligned buffers via aligned_slice and split via chunks_mut.
diskann-disk/src/utils/aligned_file_reader/storage_provider_aligned_file_reader.rs	Same migration as above for storage-provider reader tests.
diskann-disk/src/utils/aligned_file_reader/linux_aligned_file_reader.rs	Same migration as above for Linux reader tests.
diskann-disk/src/utils/aligned_file_reader/aligned_read.rs	Updates/shortens doc comment reflecting removal of wrapper type.
diskann-disk/src/search/provider/disk_vertex_provider_factory.rs	Uses aligned_slice buffer for header reads and relies on deref slicing.
diskann-disk/src/search/provider/disk_sector_graph.rs	Switches internal storage to AlignedSlice<u8> and replaces custom splitting with chunks_mut.
diskann-disk/src/search/provider/disk_provider.rs	Removes .as_slice() calls; relies on deref to slice for .to_vec().
diskann-disk/src/search/pq/quantizer_preprocess.rs	Replaces .as_mut_slice() with deref-based mutable slicing/borrows.
diskann-disk/src/search/pq/pq_scratch.rs	Replaces wrapper fields with AlignedSlice allocations and updates alignment tests.
diskann-disk/benches/benchmarks_iai/aligned_file_reader_bench_iai.rs	Updates benchmark to use aligned_slice + chunks_mut.
diskann-disk/benches/benchmarks/aligned_file_reader_bench.rs	Updates benchmark to use aligned_slice + chunks_mut.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 91.76471% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.30%. Comparing base (cfb5927) to head (3425b35).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...kann-disk/src/search/provider/disk_sector_graph.rs	71.42%	6 Missing ⚠️
diskann-disk/src/search/pq/quantizer_preprocess.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #965      +/-   ##
==========================================
- Coverage   89.31%   89.30%   -0.01%     
==========================================
  Files         447      448       +1     
  Lines       83250    83329      +79     
==========================================
+ Hits        74354    74419      +65     
- Misses       8896     8910      +14     

Flag	Coverage Δ
miri	89.30% <91.76%> (-0.01%)	⬇️
unittests	89.14% <91.76%> (-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%> (+0.97%)	⬆️
diskann-disk/src/search/provider/disk_provider.rs	90.89% <ø> (-0.01%)	⬇️
...rc/search/provider/disk_vertex_provider_factory.rs	95.70% <100.00%> (+0.05%)	⬆️
...disk/src/utils/aligned_file_reader/aligned_read.rs	100.00% <ø> (ø)
...s/aligned_file_reader/linux_aligned_file_reader.rs	82.65% <100.00%> (-0.35%)	⬇️
...ile_reader/storage_provider_aligned_file_reader.rs	98.36% <100.00%> (-0.03%)	⬇️
diskann-quantization/src/alloc/aligned_slice.rs	100.00% <100.00%> (ø)
diskann-quantization/src/alloc/mod.rs	100.00% <ø> (ø)
diskann-disk/src/search/pq/quantizer_preprocess.rs	88.00% <66.66%> (ø)
...kann-disk/src/search/provider/disk_sector_graph.rs	96.94% <71.42%> (-1.24%)	⬇️

... and 2 files with indirect coverage changes

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