feat(web): routine editor/runner UI, linked timers, routines page
- RoutineEditor component: add/remove/reorder steps, transition types, notes, save-as-template toggle, total duration display
- RoutineRunner component: countdown ring, step dots, progress bar, next step preview, pause/resume/skip/done/cancel, completion celebration
- Routine store (lib/routine-store.ts): Zustand + localStorage persistence, template management, auto-advance via tickRoutines()
- Routines page (app/routines/): template browser, active runner, ready queue, past routines
- Linked timers engine (lib/linked-timers.ts): chain building/append/remove with relinking, 3 presets (Pasta, Laundry, Meeting Prep), downstream queries
- Linked timers tests (27 tests)
- Dashboard: added Routines + nav link
- Updated roadmap.md Week 3 items
- 329 tests passing (14 test files), tsc clean
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