feat(strategy-state): persist instance-scoped slot maps

trex_core/adapters/persistence/sql/027_replace_slot_strategy_state_with_instance_map.sql

@@ -0,0 +1,18 @@
+-- REQ-0009: state is one opaque map per slot, keyed by strategy_instance_id.
+-- The old strategy_id/occupancy-scoped rows cannot be assigned an instance ID;
+-- no mapping or backfill is permitted by this contract.
+DO $$
+BEGIN
+    IF EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_schema = 'public'
+          AND table_name = 'slot_strategy_state'
+          AND column_name = 'strategy_id'
+    ) THEN
+        DROP TABLE slot_strategy_state;
+    END IF;
+END $$;
+CREATE TABLE slot_strategy_state (
+    slot_id UUID PRIMARY KEY,
+    data JSONB NOT NULL DEFAULT '{}'::jsonb
+);