Replace AlignedBoxWithSlice with Vec in PQScratch and disk fp vector caches

[wuw92]

Summary

Replaces AlignedBoxWithSlice with plain Vec for three disk-side buffers whose consumers don't require alignment.

1. PQScratch.rotated_query (diskann-disk/src/search/pq/pq_scratch.rs)

• Replace AlignedBoxWithSlice<f32> with Vec<f32>. Consumers (populate_chunk_distances via diskann-vector SIMD, TransposedTable::process_into via diskann-quantization scalar PQ table lookups) handle unaligned / arbitrary-length data, so the alignment is not load-bearing.
• PQScratch::set now tolerates query.len() >= dim, following the inmem TableL2::populate convention, instead of requiring strict equality.

2. DiskVertexProvider::aligned_vector_buf and Cache::vectors (FP_VECTOR_MEM_ALIGN)

• Replace AlignedBoxWithSlice<T> (32-byte FP_VECTOR_MEM_ALIGN) with plain Vec<T>. The fp distance kernels reached via get_vector go through diskann-vector SIMD, which handles unaligned data, so the alignment is not load-bearing.
• Neither buffer has the concurrent insert+search pattern that justifies the FastMemoryVectorProviderAsync-style 64-byte cache-line alignment: aligned_vector_buf is per-scratch-exclusive; Cache::vectors is built once via BFS then shared read-only through Arc<Cache>.
• Drop the companion memory_aligned_dimension = dims.next_multiple_of(8) padding — it was paired with the 32-byte alignment to feed 8-wide AVX tiles and is no longer justified. DiskVertexProvider and Cache now size slots to raw dim; get_vector returns a slice of length dim instead of a padded length.

[Copilot]

Pull request overview

This PR simplifies PQ query scratch handling in diskann-disk by removing unused scratch fields and alignment assumptions, and by tightening the PQScratch API to match actual production usage.

Changes:

• Remove the unused aligned_query_float buffer and drop the unused norm argument from PQScratch::set.
• Replace rotated_query from AlignedBoxWithSlice<f32> to Vec<f32> and update callers/tests accordingly.
• Rename PQScratch::new parameter from aligned_dim to dim and adjust call sites.

Reviewed changes

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

File	Description
diskann-disk/src/search/provider/disk_provider.rs	Updates the PQScratch::set call site to match the new signature (drops norm).
diskann-disk/src/search/pq/pq_scratch.rs	Removes dead scratch field, switches rotated_query storage to Vec<f32>, and simplifies set() implementation and tests.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 72.72727% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.31%. Comparing base (e497ed8) to head (f316071).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
diskann-disk/src/search/pq/pq_scratch.rs	52.63%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #960      +/-   ##
==========================================
- Coverage   89.31%   89.31%   -0.01%     
==========================================
  Files         447      447              
  Lines       83260    83250      -10     
==========================================
- Hits        74367    74354      -13     
- Misses       8893     8896       +3     

Flag	Coverage Δ
miri	89.31% <72.72%> (-0.01%)	⬇️
unittests	89.15% <72.72%> (-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/data_model/cache.rs	100.00% <100.00%> (ø)
diskann-disk/src/search/provider/disk_provider.rs	90.89% <100.00%> (+0.09%)	⬆️
...n-disk/src/search/provider/disk_vertex_provider.rs	85.27% <100.00%> (+1.31%)	⬆️
...rc/search/provider/disk_vertex_provider_factory.rs	95.65% <100.00%> (-0.02%)	⬇️
diskann-disk/src/search/pq/pq_scratch.rs	78.57% <52.63%> (-21.43%)	⬇️

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