feat: implement dry-run mode for `nstd sync` (§6.7) (#18)

spec: add dry-run mode (§6.7) (#15)

fix: freeze time in scheduler tests to prevent date drift (#16)

No-cover cleanup (#12)

build(deps): Bump actions/checkout from 4 to 6 (#14)

build(deps): Bump actions/setup-python from 5 to 6 (#13)

feat: CLI commands module (Phase 15) (#11)

feat: TUI application module (Phase 14) (#10)

feat: Setup wizard module (Phase 13) (#9)

feat: sync daemon orchestration (Phase 12) (#8)

feat: Google Calendar write (Phase 11) (#7)

feat: Google Calendar read (Phase 10) (#6)

feat: conflict detection (Phase 9) (#5)

Bump actions/setup-python from 5 to 6 (#3)

Bump actions/checkout from 4 to 6 (#2)