chore(release): v1.4.2

[gloryfromca]

Summary

Cut 1.4.2: the index-key fix (#481) with its follow-ups (#487) and the knowledge category fix (#469). Version bump, regenerated docs/openapi.json, and the CHANGELOG's Unreleased entries moved under ## [1.4.2] with the release page's lead paragraph and ### Upgrade group (LanceDB: nothing to do; Milvus: one rebuild; the two LanceDB roots that need a command).

Area

• Architecture method
• Benchmark
• Use case
• Documentation
• Developer experience
• CI, build, or release

Verification

uv sync && uv run python -c "import everos; print(everos.__version__)"   # 1.4.2
uv run python scripts/dump_openapi.py                                      # docs/openapi.json -> 1.4.2
make lint                                                                  # OK (openapi drift check included)
make check-commits RANGE=origin/main..HEAD
make check-cjk                                                             # 10 pre-existing hits, none in files this PR touches

Checklist

• I kept the change scoped to the relevant area.
• I am opening this from a separate branch, not pushing directly to main.
• I updated docs, examples, or setup notes when behavior changed.
• I added or updated tests when the change affects behavior. (Release metadata only.)
• I did not commit secrets, .env files, dependency folders, or generated output.
• Active relative links in Markdown files resolve.

Notes for Reviewers

• After merge: git tag -a v1.4.2 -m v1.4.2 && git push origin v1.4.2, approve the release environment in the Actions run, verify https://pypi.org/project/everos/1.4.2/, then publish the drafted GitHub Release page (its body is lifted from this CHANGELOG section).

🤖 Generated with Claude Code

[gloryfromca]

Holding the release: more code lands on main first. Will reopen a fresh release PR when it is time.