Add an ephemeral live-run presence channel (separate from the durable
iCloud progress sync) so a propped-up iPhone can mirror the Watch's
Ready → work/rest → Finish flow in real time as the user swipes.
Watch drives, phone mirrors (read-only), so there's no echo loop:
- Watch's ExerciseProgressView broadcasts a LiveProgress frame on every
phase transition (and an ended signal on leave) via sendMessage,
reachable-only — throwaway presence, never written to iCloud.
- Timers ride as wall-clock anchors (Date kept native in the WC dict to
preserve sub-second precision), so both devices count independently
off shared start times and stay in lockstep without streaming ticks.
- Phone holds a transient LiveRunState; ContentView auto-presents a
read-only LiveProgressMirrorView full-screen cover while a run is live.
Claude-Session: https://claude.ai/code/session_01SCv7zvGFcKy47KSTnTLxRe
