Remove synthetic/structured data generation from diskann-providers

[JordanMaples]

This is a follow up PR for #904, which has an outdated baseline and can be closed with this superseding it.
Essentially the same work was done here just without the provider/async_/caching changes. This closes #903.

When #953 merges, the from_dim definition will need to be updated to support the '2' case.

Replace generate_structured_data.rs and generate_synthetic_labels_utils.rs with diskann::graph::test::synthetic::Grid and diskann-tools' own label generator respectively.

• Rewrite GenerateGrid trait impls to delegate to Grid::data/data_as
• Replace all adj list generation calls with Grid::neighbors
• Rewire generate_synthetic_labels binary to diskann-tools version
• Delete both redundant utility files and clean up exports

[Copilot]

Pull request overview

This PR removes redundant synthetic/structured data generation utilities from diskann-providers by migrating grid generation to diskann::graph::test::synthetic::Grid and rewiring the synthetic label generation CLI to use diskann-tools’ label generator.

Changes:

• Add Grid::from_dim() helper (plus tests) to construct a supported Grid from a dimension count.
• Update diskann-providers async/caching tests to generate grid vectors + adjacency lists via Grid::{data,data_as,neighbors}.
• Rewire diskann-tools generate_synthetic_labels binary to call diskann_tools::utils::generate_labels and delete the old diskann-providers label/grid generator utilities + exports.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
diskann/src/graph/test/synthetic.rs	Adds Grid::from_dim() and tests to support dimension→Grid construction for migrated callers.
diskann-tools/src/bin/generate_synthetic_labels.rs	Switches the CLI to diskann-tools label generation util and passes a storage provider.
diskann-providers/src/utils/mod.rs	Removes public exports for the deleted structured-data + synthetic-label utils.
diskann-providers/src/utils/generate_synthetic_labels_utils.rs	Deletes the old label generator implementation (now sourced from diskann-tools).
diskann-providers/src/utils/generate_structured_data.rs	Deletes the old grid/circle structured data generator implementation (now sourced from diskann::graph::test::synthetic::Grid).
diskann-providers/src/model/graph/provider/async_/caching/example.rs	Updates adjacency generation to use Grid::neighbors via async_tests::grid_from_dim.
diskann-providers/src/index/diskann_async.rs	Rewrites GenerateGrid impls + adjacency generation to delegate to Grid::data/data_as/neighbors.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 97.29730% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.47%. Comparing base (a0dfde6) to head (6fa8471).

Files with missing lines	Patch %	Lines
diskann-tools/src/bin/generate_synthetic_labels.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #963      +/-   ##
==========================================
+ Coverage   89.31%   90.47%   +1.16%     
==========================================
  Files         448      446       -2     
  Lines       83329    83076     -253     
==========================================
+ Hits        74422    75160     +738     
+ Misses       8907     7916     -991     

Flag	Coverage Δ
miri	90.47% <97.29%> (+1.16%)	⬆️
unittests	90.43% <97.29%> (+1.28%)	⬆️

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

Files with missing lines	Coverage Δ
diskann-providers/src/index/diskann_async.rs	96.42% <100.00%> (+0.12%)	⬆️
diskann/src/graph/test/synthetic.rs	100.00% <100.00%> (ø)
diskann-tools/src/bin/generate_synthetic_labels.rs	0.00% <0.00%> (ø)

... and 39 files with indirect coverage changes

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