feat(agents): quiet window + peak hours + tz prefs for time-of-day agent (#112)

Adds four InferredParams (all TTL=24h, min_history=50 except preferred_hour=10):
- quiet_start / quiet_end: longest contiguous below-baseline hour run (HH:MM)
- peak_hours: top-quartile done-event hours, sorted ascending
- tz: cold-start only ("UTC"); populated from auth provider, no inference function

compute() updated:
- in_quiet check (quiet window) takes precedence over peak hours
- in_peak emits "peak productivity hour" language when current hour is in peak_hours
- approaching peak (within 2h) surfaces for orchestrator timing
- tz surfaced in snippet header when not UTC
- snapshot adds peak_hours, in_quiet, in_peak, tz

- Agent bumped to v1.2.0
- 21 new tests: night-owl, early-bird, shift-worker, quiet/peak snippet rendering
- Fixed test_snapshot_keys in test_agents.py to include new snapshot fields

Closes #112

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ml/agents/tests/test_agents.py

@@ -153,7 +153,8 @@ class TestTimeOfDayAgent:
 
     def test_snapshot_keys(self):
         out = self.agent.compute(_inp())
-        assert {"hour", "day_of_week", "preferred_hour", "quiet_start", "quiet_end"} == set(out.signals_snapshot)
+        assert {"hour", "day_of_week", "preferred_hour", "quiet_start", "quiet_end",
+                "peak_hours", "in_quiet", "in_peak", "tz"} == set(out.signals_snapshot)
 
 
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