ci(test-windows): retry the transient ChromaDB HNSW compaction flake

[igorls]

Problem

test-windows goes red at random. The failure is always the same family —
ChromaDB's rust HNSW core failing compaction on Windows:

chromadb.errors.InternalError: Error in compaction: Failed to apply logs to the hnsw segment writer

It is not caused by our code: migrate.py / the affected tests are
unchanged across the runs, it hits different tests (test_migrate_wings,
test_closets) on unrelated commits, and it does not reproduce on
Linux/macOS. Across a single batch of merges this week roughly half the
test-windows runs passed and half failed on the same code. CLAUDE.md already
documents Windows ChromaDB instability (the Windows coverage threshold is
lowered for the same reason). It has been turning otherwise-green release runs
red and forcing manual re-runs.

Fix

Add pytest-rerunfailures and, only on the test-windows job, retry that
specific transient error:

--reruns 2 --reruns-delay 5 --only-rerun "Failed to apply logs to the hnsw segment writer"

• --only-rerun scopes the retry to this one native-dependency error, so a
  real, deterministic test failure still fails on the first attempt — nothing
  is masked.
• The Linux and macOS jobs keep zero reruns, so genuine regressions surface
  there loudly and immediately.
• pytest-rerunfailures is added to both dev dependency lists
  ([project.optional-dependencies].dev for pip/CI and [dependency-groups].dev
  for uv); zero runtime cost (test-only).

Notes

If a different Windows flake recurs (e.g. the occasional test_closets
ranking assertion), extend the --only-rerun pattern or investigate that one
on its own merits rather than broadening to a blanket retry.

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[gemini-code-assist]

Code Review

This pull request adds the pytest-rerunfailures dependency to the development dependencies in pyproject.toml to handle transient ChromaDB-on-Windows HNSW compaction failures in CI. There are no review comments, and I have no additional feedback to provide.

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