fix: preserve multi-cause reconcile warnings and align slot blocking

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

trex_core/adapters/persistence/sql/016_create_slot_reconcile_warning.sql

@@ -1,6 +1,6 @@
 -- BAT-050 / REQ-102: reconcile-warning durable store (dcy-034).
--- PK: slot_id (TEXT, UUID string). pause_store 동형 설계.
--- ON CONFLICT DO UPDATE: 동일 slot_id 재삽입 시 최신 값으로 갱신.
+-- Initial schema; migration 028 upgrades PK to (slot_id, case_code)
+-- so B/C causes can coexist for the same slot.
 CREATE TABLE IF NOT EXISTS slot_reconcile_warning (
     slot_id      TEXT        PRIMARY KEY,
     portfolio_id TEXT        NOT NULL,

trex_core/adapters/persistence/sql/028_preserve_reconcile_warning_cases.sql

@@ -0,0 +1,7 @@
+-- REQ-123 / issue #83:
+-- Preserve simultaneous warning causes by keying warnings per (slot_id, case_code).
+ALTER TABLE slot_reconcile_warning
+    DROP CONSTRAINT IF EXISTS slot_reconcile_warning_pkey;
+
+ALTER TABLE slot_reconcile_warning
+    ADD CONSTRAINT slot_reconcile_warning_pkey PRIMARY KEY (slot_id, case_code);