test: add 14 unit tests for state lib (load/save/log/rotation)

[TerminalGravity]

Adds comprehensive test coverage for src/lib/state.ts:

• now(): validates ISO format and timing accuracy
• loadState/saveState: missing files, corrupt JSON, round-trips, overwrites, auto-creates state dir
• appendLog/readLog: missing/empty files, append+read, lastN slicing, corrupt line handling, 5MB rotation, auto-creates state dir

All 57 tests pass (14 new + 43 existing).

[TerminalGravity]

Example configs are really well commented — exactly what new users need. The triage.yml and contract examples make the config surface much more approachable.

Small suggestion: in the README callout, link directly to examples/.preflight/README.md so people can browse the structure on GitHub before cloning. LGTM.

[TerminalGravity]

14 tests for state lib is solid coverage. Load/save/log/rotation are the core persistence paths so this is valuable.

[TerminalGravity]

Closing — superseded by a newer version of this test PR.