feat(backend): demo scheduler on the virtual clock — doses, missed, check-ins, scales, silence

- app/scheduler/demo.py: run_until(now) replays due and fresh events in time order: dose rows +
  med_reminder, missed after 2 h without an answer → monitoring, daily_checkin, scale_due by the
  config/modules.yaml schedules, daily monitoring pass (silence, missed doses) → reach_out/scale_due
- idempotent via scheduler_events (unique token+key); stale events are not sent; no contact without
  consent or during an open crisis
- config/scheduler.yaml: times and windows; runs while the questionnaire release is off
- POST /demo/clock/advance replays the scheduler up to the new time

Refs #13

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

app/db/bootstrap.py

@@ -5,6 +5,7 @@ The only module (besides registration code) that touches both schemas — and on
 
 from app.db import audit as _audit  # noqa: F401  (registers audit_log in clinical metadata)
 from app.db import intake as _intake  # noqa: F401
+from app.db import scheduler as _scheduler  # noqa: F401
 from app.db.clinical import ClinicalBase
 from app.db.identity import IdentityBase
 from app.db.session import clinical_engine, identity_engine

app/db/scheduler.py

@@ -0,0 +1,24 @@
+"""Delivery log of the demo scheduler (#13): one row per delivered event, the unique key makes runs idempotent.
+
+Clinical DB, keyed by token only (guardrail #5). Created by `init_db` (`app.db.bootstrap`).
+"""
+
+from datetime import datetime
+
+from sqlalchemy import String, UniqueConstraint
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.clinical import TOKEN_LEN, BigId, ClinicalBase
+from app.db.types import TZDateTime
+
+
+class SchedulerEvent(ClinicalBase):
+    __tablename__ = "scheduler_events"
+    __table_args__ = (UniqueConstraint("token", "key", name="uq_scheduler_events_token_key"),)
+
+    id: Mapped[int] = mapped_column(BigId, primary_key=True, autoincrement=True)
+    token: Mapped[str] = mapped_column(String(TOKEN_LEN))
+    key: Mapped[str] = mapped_column(String(96))  # e.g. "dose:3:2026-10-06T08:00", "checkin:2026-10-06"
+    kind: Mapped[str] = mapped_column(String(32))  # med_reminder | missed | daily_checkin | scale_due | evaluation
+    due_at: Mapped[datetime] = mapped_column(TZDateTime)
+    done_at: Mapped[datetime] = mapped_column(TZDateTime)