Deliver BAT-002: slot-core daemon + HTTP intent API + PostgreSQL

Implement REQ-005~009 (dcy-002 slice 1) as an onion stack on top of the
BAT-001 pure domain:
- application: IntentService (admission + single-writer transition +
  intent_id idempotency via durable intent_log)
- adapters/persistence: PostgreSQLSlotRepository + PostgreSQLIntentStore +
  trex-core-owned migrations (daily_slot per Appendix A, daily_symbol_entries,
  slot_transition_log, intent_log) + in-memory intent store
- adapters/api: FastAPI /v1 (healthz, intents/buy|sell|{id}, slots, capacity)
- runtime: trex-core-daemon entrypoint with lifespan migrate+preallocate

Verification (against local PostgreSQL 18): 74 passed, ruff clean, domain
import sweep shows zero web/db deps (NFR-1), 20-thread concurrency admits
exactly the idle count (NFR-2), idempotent resubmit causes no double
transition (NFR-3), EXPECTED_SLOT_FIELDS<->information_schema drift test
(realizes dcy-001 OQ-2's deferred DB-side check), and a daemon E2E smoke.

Align all four baseline docs to the new daemon/API/persistence layers.
BAT-002 -> release-candidate; REQ-005~009 -> Implemented. Full async outbox,
broker execution, safety floor, and strategy daemons remain deferred to a
follow-up Discovery.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

trex_core/application/ports.py

@@ -0,0 +1,49 @@
+"""Application ports (REQ-007). The intent dedup/audit store contract.
+
+Kept in the application layer (not domain) so the pure slot domain stays
+unaware of the intent concept. Concrete implementations live in adapters.
+"""
+from __future__ import annotations
+
+from typing import Optional, Protocol
+from uuid import UUID
+
+
+class IntentStore(Protocol):
+    """Durable idempotency + audit store for accepted intents (dcy-002 OQ-1).
+
+    `try_insert` is the dedup gate: it returns False if `intent_id` already
+    exists, which prevents a duplicate intent from re-driving a slot
+    transition (NFR-3). `finalize` records the decision after processing.
+    """
+
+    def try_insert(self, intent_id: str, intent_type: str, payload: dict) -> bool:
+        """Insert a new intent row in 'processing' state.
+
+        Returns True if newly inserted, False if `intent_id` already exists.
+        """
+        ...
+
+    def get(self, intent_id: str) -> Optional["IntentRecord"]:
+        """Return the stored intent record, or None."""
+        ...
+
+    def finalize(
+        self,
+        intent_id: str,
+        status: str,
+        slot_id: Optional[UUID],
+        reason: Optional[str],
+    ) -> None:
+        """Update an intent row with its final decision (admitted/rejected)."""
+        ...
+
+
+class IntentRecord:
+    """Snapshot of an intent_log row (duck-typed; see adapters)."""
+
+    intent_id: str
+    intent_type: str
+    status: str
+    slot_id: Optional[UUID]
+    reason: Optional[str]