chore: bump version to 0.1.6

[cyfyifanchen]

Summary

Bump Raven package metadata from 0.1.5 to 0.1.6 so the release tag can build a wheel from the current main branch.

This release carries the changes merged after v0.1.5:

• Version display now derives from installed package metadata (fix: derive __version__ from installed package metadata #139).
• Tracing dashboard port reuse avoids taking over non-Raven viewers (fix(tracing): reuse the dashboard port only when it is our own viewer #141).
• CLI startup defers LiteLLM imports for faster cold start (perf(cli): defer litellm import to cut cold start #147).
• Self-evolution stack and AppWorld benchmark entry points are included (feat(*): self-evolution stack: evolver, appworld bench, unified entry #140).
• TUI render delay is reduced by deferring provider and memory loading (perf(tui): cut render delay by deferring provider and memory #157).

Type

• Fix
• Feature
• Docs
• CI / tooling
• Refactor
• Other

Verification

• Relevant tests pass locally
• Relevant lint / type checks pass locally
• User-facing docs or screenshots are updated when needed

Commands run:

• PYTHONPATH=. uv run pytest tests/test_cli_smoke.py::test_version_flag_matches_installed_metadata -q
• make check-commits COMMIT_RANGE=origin/main..HEAD
• PYTHONPATH=. uv run python scripts/check_commit_file.py /tmp/raven-commit-msg.txt

No user-facing docs or screenshots were needed for this version metadata bump; release notes will be published with the GitHub Release.

Risk

• Security impact considered
• Backward compatibility considered
• Rollback path is clear for risky changes

This changes package metadata only. Rollback is to delete the v0.1.6 tag/release if publication fails before users upgrade, or publish a follow-up patch release if a released package issue is found.

Related Issues

N/A