repo hygiene: remove committed build artifacts and stale config.bak
- Remove coverage/ directory (HTML and lcov files)
- Remove lcov.info and librust_out.rlib build artifacts
- Remove stray file '1' at repo root
- Remove dead config.bak/ module (unreferenced backup)
- Update .gitignore to exclude coverage/, lcov.info, and *.rlib patterns
Verified:
- No references to config.bak or librust_out in codebase
- cargo check --workspace compiles successfully
- notes/, .beads/, tests/, dashboards/ untouched
f07ba9575b