feat(core): rule engine for alerts/agent actions and virtual demo clock

- app/core/clock.py: now()/today(), virtual offset (advance/set_now/reset),
  pluggable offset persistence hook (ADR-005)
- config/rules.yaml + app/core/rules.py: YAML declares rules (params, actions,
  levels, reason_ru), Python evaluators implement predicates by id; dedup of
  open alerts, crisis never suppressed; ADR-006 colours (ADR-007)
- tests: per-rule unit tests, dedup, clock, 13-day demo persona trajectory

Refs #5

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_clock.py

@@ -0,0 +1,70 @@
+from collections.abc import Iterator
+from datetime import datetime, timedelta
+
+import pytest
+
+from app.config import Settings
+from app.core import clock
+
+
+@pytest.fixture(autouse=True)
+def _fresh_clock(monkeypatch: pytest.MonkeyPatch) -> Iterator[None]:
+    monkeypatch.setattr(clock, "get_settings", lambda: Settings(_env_file=None, demo_clock=True))
+    clock.register_persistence(None, None)
+    clock.reset()
+    yield
+    clock.register_persistence(None, None)
+    clock.reset()
+
+
+def _close(a: datetime, b: datetime) -> bool:
+    return abs(a - b) < timedelta(seconds=5)
+
+
+def test_now_is_tz_aware_in_settings_tz() -> None:
+    now = clock.now()
+    assert now.tzinfo is not None
+    assert now.utcoffset() == timedelta(hours=3)  # Europe/Moscow
+
+
+def test_advance_shifts_time() -> None:
+    before = clock.now()
+    after = clock.advance(days=1, hours=2, minutes=30)
+    assert _close(after, before + timedelta(days=1, hours=2, minutes=30))
+    assert clock.offset() == timedelta(days=1, hours=2, minutes=30)
+    assert clock.today() == clock.now().date()
+
+
+def test_set_now_and_reset() -> None:
+    target = datetime(2026, 10, 20, 9, 0)
+    assert _close(clock.set_now(target), target.replace(tzinfo=clock.now().tzinfo))
+    clock.reset()
+    assert clock.offset() == timedelta(0)
+    assert _close(clock.now(), clock._real_now())
+
+
+def test_persistence_hook_loads_and_saves() -> None:
+    saved: list[timedelta] = []
+    clock.register_persistence(lambda: timedelta(days=5), saved.append)
+    assert clock.offset() == timedelta(days=5)
+    clock.advance(days=1)
+    assert saved[-1] == timedelta(days=6)
+    clock.reset()
+    assert saved[-1] == timedelta(0)
+
+
+def test_persistence_load_none_keeps_offset() -> None:
+    clock.advance(hours=3)
+    clock.register_persistence(lambda: None, None)
+    assert clock.offset() == timedelta(hours=3)
+
+
+def test_real_mode_ignores_offset_and_forbids_moving(monkeypatch: pytest.MonkeyPatch) -> None:
+    clock.advance(days=3)
+    monkeypatch.setattr(clock, "get_settings", lambda: Settings(_env_file=None, demo_clock=False))
+    assert clock.offset() == timedelta(0)
+    assert _close(clock.now(), clock._real_now())
+    with pytest.raises(RuntimeError):
+        clock.advance(days=1)
+    with pytest.raises(RuntimeError):
+        clock.set_now(datetime(2026, 1, 1))