Phase 2: persistence + safety controls

Aggiunge la persistenza SQLite, l'audit log a hash chain, il kill
switch coordinato e i CLI di gestione documentati in
docs/05-data-model.md e docs/07-risk-controls.md. 197 test pass,
1 skipped (sqlite3 CLI mancante), copertura totale 97%.

State (`state/`):
- 0001_init.sql con positions, instructions, decisions, dvol_history,
  manual_actions, system_state.
- db.py: connect con WAL + foreign_keys + transaction ctx, runner
  forward-only basato su PRAGMA user_version.
- models.py: record Pydantic, Decimal preservato come TEXT.
- repository.py: CRUD typed con singola connessione passata, cache
  aware, posizioni concorrenti.

Safety (`safety/`):
- audit_log.py: AuditLog append-only con SHA-256 chain e fsync,
  verify_chain riconosce ogni manomissione (payload, prev_hash,
  hash, JSON, separatori).
- kill_switch.py: arm/disarm transazionali, idempotenti, accoppiati
  all'audit chain.

Config (`config/loader.py` + `strategy.yaml`):
- Loader YAML con deep-merge di strategy.local.yaml.
- Verifica config_hash SHA-256 (riga config_hash esclusa).
- File golden strategy.yaml + esempio override.

Scripts:
- dead_man.sh: watchdog shell indipendente da Python.
- backup.py: VACUUM INTO orario con retention 30 giorni.

CLI:
- audit verify (exit 2 su tampering).
- kill-switch arm/disarm/status su SQLite reale.
- state inspect con tabella posizioni aperte.
- config hash, config validate.

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

tests/integration/test_dead_man_sh.py

@@ -0,0 +1,111 @@
+"""Smoke tests for the dead_man.sh shell watchdog."""
+
+from __future__ import annotations
+
+import shutil
+import sqlite3
+import subprocess
+from datetime import UTC, datetime, timedelta
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+SCRIPT = REPO_ROOT / "scripts" / "dead_man.sh"
+
+_SQLITE3_BIN = shutil.which("sqlite3")
+
+pytestmark = [
+    pytest.mark.integration,
+]
+
+
+def _require_sqlite3() -> None:
+    if _SQLITE3_BIN is None:
+        pytest.skip("sqlite3 CLI not installed on this host")
+
+
+def _setup_project(tmp_path: Path) -> Path:
+    project = tmp_path / "project"
+    (project / "data" / "log").mkdir(parents=True)
+    (project / "scripts").mkdir(parents=True)
+    shutil.copy(SCRIPT, project / "scripts" / "dead_man.sh")
+    return project
+
+
+def _write_health(project: Path, ts: datetime) -> None:
+    log_file = project / "data" / "log" / f"cerbero-bite-{ts:%Y-%m-%d}.jsonl"
+    log_file.write_text(
+        f'{{"ts": "{ts.astimezone(UTC).isoformat()}", "event": "HEALTH_OK"}}\n',
+        encoding="utf-8",
+    )
+
+
+def _run(project: Path, threshold: int = 900) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(
+        ["bash", str(project / "scripts" / "dead_man.sh")],
+        env={
+            "PATH": "/usr/bin:/bin",
+            "PROJECT_ROOT": str(project),
+            "DEAD_MAN_THRESHOLD_SECONDS": str(threshold),
+        },
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+
+def test_dead_man_exits_zero_when_recent_health_ok(tmp_path: Path) -> None:
+    project = _setup_project(tmp_path)
+    _write_health(project, datetime.now(UTC) - timedelta(seconds=60))
+    result = _run(project, threshold=900)
+    assert result.returncode == 0, result.stderr
+
+
+def test_dead_man_arms_kill_switch_when_silent(tmp_path: Path) -> None:
+    _require_sqlite3()
+    project = _setup_project(tmp_path)
+    _write_health(project, datetime.now(UTC) - timedelta(seconds=2000))
+
+    # Pre-create the SQLite system_state singleton; otherwise the script
+    # has nothing to update.
+    db = project / "data" / "state.sqlite"
+    conn = sqlite3.connect(str(db))
+    conn.execute(
+        "CREATE TABLE system_state (id INTEGER PRIMARY KEY CHECK(id=1), "
+        "kill_switch INTEGER NOT NULL DEFAULT 0, kill_reason TEXT, "
+        "kill_at TEXT, last_health_check TEXT NOT NULL, "
+        "last_kelly_calib TEXT, config_version TEXT NOT NULL, "
+        "started_at TEXT NOT NULL)"
+    )
+    conn.execute(
+        "INSERT INTO system_state(id, last_health_check, config_version, started_at) "
+        "VALUES (1, '2026-04-27', '1.0.0', '2026-04-27')"
+    )
+    conn.commit()
+    conn.close()
+
+    result = _run(project, threshold=900)
+    assert result.returncode == 1
+
+    # Kill switch armed.
+    conn = sqlite3.connect(str(db))
+    try:
+        kill = conn.execute("SELECT kill_switch FROM system_state").fetchone()[0]
+    finally:
+        conn.close()
+    assert kill == 1
+
+    # Alert file exists.
+    alert = project / "data" / "log" / "dead-man-alert.txt"
+    assert alert.exists()
+    assert "dead_man" in alert.read_text(encoding="utf-8")
+
+
+def test_dead_man_handles_missing_log_file(tmp_path: Path) -> None:
+    project = _setup_project(tmp_path)
+    # No log file at all.
+    result = _run(project, threshold=900)
+    assert result.returncode == 1
+    alert = project / "data" / "log" / "dead-man-alert.txt"
+    assert alert.exists()