chore: release hotdata-langchain v0.5.0

[rohan-hotdata]

Summary

Release hotdata-langchain v0.5.0.

Checklist

• Version bumped in pyproject.toml
• CHANGELOG.md updated
• CI green

After merge, run ./scripts/release.sh publish from a clean main checkout.

[claude]

Release mechanics check out: pyproject.toml 0.4.0 → 0.5.0, matching uv.lock entry for the editable root package, and a ## [0.5.0] - 2026-08-07 section that captures the previous [Unreleased] notes verbatim — so scripts/check-release.py and the tag check in scripts/publish-workflow.sh will have what they need. Minor bump is right for an additive create_index() plus a floor raise on hotdata-framework>=0.10.0 (already in pyproject.toml), and no version constant needs bumping since hotdata_langchain/__init__.py reads it from package metadata.

Note that CI had not reported yet when this review ran (Test 3.12 and the release-metadata check were still queued/in progress), so this approval covers the diff, not a green build — confirm both before merging and tagging.