Fix coverage warnings from orphaned .pyc files in muse/
Tests were writing temporary hook/prompt files directly into muse/ and
only cleaning up the .py sources, leaving .pyc bytecache behind.
Coverage's source=muse directive then tried to report on those orphans.
- Monkeypatch think.muse.MUSE_DIR to tmp_path in 8 tests so test files
never touch the real muse/ directory
- Remove try/finally cleanup blocks (tmp_path auto-cleans)
- Add [report] omit for __pycache__ in .coveragerc as defense in depth
- Delete 6 stale .pyc files from muse/__pycache__/
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>