Add rerun, rdeps, and notify commands to day10 CLI
- rerun: retry failed builds by hash or package name, with --force to clear cached layers
- rdeps: reverse dependency lookup from cached solutions, with --failing filter
- notify: pluggable notification system supporting slack, zulip, telegram, email, stdout
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>