Consistency and maintenance cleanup
- Standardize error handling: all 9 command files use instanceof guard
- Extract shared CAP_COLLECTION constant to src/lib/constants.js
- Add DID validation to ship and skim (fail fast with clear message)
- Normalize ship command declaration to .command().argument() pattern
- Use single timestamp per ship operation
- Add @atproto/common-web to package.json dependencies
- Extract shared test run() helper to test/helpers.js
- Add .vit/.gitignore to ignore local JSONL logs
- Fix docs: correct doctor/init alias claims, login syntax, add beacon
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>