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>

src/cerbero_bite/state/models.py

@@ -0,0 +1,154 @@
+"""Pydantic record types mirroring the SQLite tables.
+
+Every numeric column documented as ``NUMERIC`` in
+``state/migrations/0001_init.sql`` is exposed as :class:`decimal.Decimal`
+on the Python side. The repository layer is responsible for serialising
+to ``TEXT`` (using ``str``) when writing and parsing back when reading,
+so precision is never lost via ``float`` coercion.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime
+from decimal import Decimal
+from typing import Literal
+from uuid import UUID
+
+from pydantic import BaseModel, ConfigDict, Field
+
+__all__ = [
+    "DecisionRecord",
+    "DvolSnapshot",
+    "InstructionRecord",
+    "ManualAction",
+    "PositionRecord",
+    "PositionStatus",
+    "SystemStateRecord",
+]
+
+
+PositionStatus = Literal[
+    "proposed",
+    "awaiting_fill",
+    "open",
+    "closing",
+    "closed",
+    "cancelled",
+]
+
+
+class PositionRecord(BaseModel):
+    """Row of the ``positions`` table."""
+
+    model_config = ConfigDict(extra="forbid")
+
+    proposal_id: UUID
+    spread_type: str
+    asset: str = "ETH"
+    expiry: datetime
+    short_strike: Decimal
+    long_strike: Decimal
+    short_instrument: str
+    long_instrument: str
+    n_contracts: int
+    spread_width_usd: Decimal
+    spread_width_pct: Decimal
+    credit_eth: Decimal
+    credit_usd: Decimal
+    max_loss_usd: Decimal
+    spot_at_entry: Decimal
+    dvol_at_entry: Decimal
+    delta_at_entry: Decimal
+    eth_price_at_entry: Decimal
+    proposed_at: datetime
+    opened_at: datetime | None = None
+    closed_at: datetime | None = None
+    close_reason: str | None = None
+    debit_paid_eth: Decimal | None = None
+    pnl_eth: Decimal | None = None
+    pnl_usd: Decimal | None = None
+    status: PositionStatus
+    created_at: datetime
+    updated_at: datetime
+
+
+class InstructionRecord(BaseModel):
+    """Row of the ``instructions`` table."""
+
+    model_config = ConfigDict(extra="forbid")
+
+    instruction_id: UUID
+    proposal_id: UUID
+    kind: Literal["open_combo", "close_combo"]
+    payload_json: str
+    sent_at: datetime
+    acknowledged_at: datetime | None = None
+    filled_at: datetime | None = None
+    cancelled_at: datetime | None = None
+    actual_fill_eth: Decimal | None = None
+    actual_fees_eth: Decimal | None = None
+
+
+class DecisionRecord(BaseModel):
+    """Row of the ``decisions`` table.
+
+    ``id`` is :class:`int` and may be ``None`` before the row has been
+    inserted; the repository sets it after the auto-increment fires.
+    """
+
+    model_config = ConfigDict(extra="forbid")
+
+    id: int | None = None
+    decision_type: Literal["entry_check", "exit_check", "kelly_recalib"]
+    proposal_id: UUID | None = None
+    timestamp: datetime
+    inputs_json: str
+    outputs_json: str
+    action_taken: str | None = None
+    notes: str | None = None
+
+
+class DvolSnapshot(BaseModel):
+    """Row of the ``dvol_history`` table."""
+
+    model_config = ConfigDict(extra="forbid")
+
+    timestamp: datetime
+    dvol: Decimal
+    eth_spot: Decimal
+
+
+class ManualAction(BaseModel):
+    """Row of the ``manual_actions`` table."""
+
+    model_config = ConfigDict(extra="forbid")
+
+    id: int | None = None
+    kind: Literal[
+        "approve_proposal",
+        "reject_proposal",
+        "force_close",
+        "arm_kill",
+        "disarm_kill",
+    ]
+    proposal_id: UUID | None = None
+    payload_json: str | None = None
+    created_at: datetime
+    consumed_at: datetime | None = None
+    consumed_by: str | None = None
+    result: str | None = None
+
+
+class SystemStateRecord(BaseModel):
+    """Singleton row of the ``system_state`` table."""
+
+    model_config = ConfigDict(extra="forbid")
+
+    id: int = Field(default=1)
+    kill_switch: int = 0
+    kill_reason: str | None = None
+    kill_at: datetime | None = None
+    last_health_check: datetime
+    last_kelly_calib: datetime | None = None
+    config_version: str
+    started_at: datetime