Add Start/Stop Workout Button and Timer Display

[arii]

• Status: OPEN (Linked to PR Add Start/Stop Workout button and timer display #697)
  • Priority: Medium
  • Context:
    The main dashboard lacks direct control over the global workout timer. Administrators must currently use a separate control panel or debugging tools to manage the session state (WORK, REST, PAUSE).
  • Technical Analysis:
    • Current Gap: While types/websocket.ts defines TimerCommandMessage with START and STOP commands, there is no corresponding UI component on the dashboard to trigger them. The file components/WorkoutControls.tsx is missing from the codebase.
    • Required Change:
      1. New Component: Create components/WorkoutControls.tsx featuring "Start" (Play icon) and "Stop" (Square icon) buttons.
      2. Integration: Wire the buttons to emit TIMER_COMMAND WebSocket messages.
      3. Display: Add a large, high-visibility timer readout (MM:SS) that subscribes to the timerData.timeRemaining broadcast.

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Cloned from #710

[arii]

Consolidated into #895

[arii]

don't like this feature