v1.10.0

What's Changed

• Add cn usage setup --watch for one-command Codex/Claude usage alert setup.
• Add macOS/Linux background usage watcher commands: cn usage watch start, stop, restart, and status.
• Show watcher state in cn usage status.
• Refresh README usage alert setup docs with terminal demo and Slack/Discord reset alert routing.
• Add Windows guided usage setup support for configuring usage alert preferences.

Verification

• bash scripts/run_tests.sh passed: 26/26 tests.
• npm pack --dry-run verified package contents for code-notify@1.10.0.