refactor(agent-office): drop the random idle→break→idle cycle

The pixel-office game UI is gone, so simulating coffee-break /
nap / walk states no longer serves any purpose. Remove:
- scheduler's _check_idle_breaks job (no more 60s idle scan)
- BaseAgent.check_idle_break() and _break_until field
- 'break' from VALID_STATES and from transition() branches
- IDLE_BREAK_THRESHOLD / BREAK_DURATION_MIN / BREAK_DURATION_MAX
  config knobs
- 'idle/break' guard in each agent's on_schedule (now just 'idle')

Agents now sit in 'idle' between scheduled jobs and explicit
commands. Display reads 'Idle' instead of churning between idle
and break.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

agent-office/app/scheduler.py

@@ -5,10 +5,6 @@ from .agents import AGENT_REGISTRY
 
 scheduler = AsyncIOScheduler(timezone="Asia/Seoul")
 
-async def _check_idle_breaks():
-    for agent in AGENT_REGISTRY.values():
-        await agent.check_idle_break()
-
 async def _run_stock_schedule():
     agent = AGENT_REGISTRY.get("stock")
     if agent:
@@ -78,6 +74,5 @@ def init_scheduler():
     scheduler.add_job(_run_lotto_schedule, "cron", day_of_week="mon", hour=9, minute=0, id="lotto_curate")
     scheduler.add_job(_run_youtube_research, "cron", hour=9, minute=0, id="youtube_research")
     scheduler.add_job(_send_youtube_weekly_report, "cron", day_of_week="mon", hour=8, minute=0, id="youtube_weekly_report")
-    scheduler.add_job(_check_idle_breaks, "interval", seconds=60, id="idle_check")
     scheduler.add_job(_poll_pipelines, "interval", seconds=30, id="pipeline_poll")
     scheduler.start()