fix: align schema 15 settlement tests and integer validation

tests/test_month_settlement_schema.py

@@ -13,11 +13,11 @@ def _insert_sql():
         VALUES (?, ?, ?, 'draft', 1, 'tester', '2026-10-15T00:00:00+09:00', 'tester', '2026-10-15T00:00:00+09:00')"""
 
 
-def test_fresh_db_has_month_settlement_schema_16_without_latest_run_id(tmp_path):
+def test_fresh_db_has_month_settlement_schema_15_without_latest_run_id(tmp_path):
     path = str(tmp_path / "fresh.sqlite3")
     init_db(path)
     with sqlite3.connect(path) as conn:
-        assert conn.execute("SELECT value FROM schema_meta WHERE key='schema_version'").fetchone()[0] == "16"
+        assert conn.execute("SELECT value FROM schema_meta WHERE key='schema_version'").fetchone()[0] == "15"
         assert conn.execute("SELECT COUNT(*) FROM sqlite_master WHERE type='table' AND name='monthly_settlement'").fetchone()[0] == 1
         columns = {row[1]: row for row in conn.execute("PRAGMA table_info(monthly_settlement)")}
         assert columns["approval_flags_json"][4] == "'{}'"
@@ -57,7 +57,7 @@ def test_schema15_upgrade_drops_only_latest_run_id_and_preserves_closed_row(tmp_
     init_db(path)
     init_db(path)
     with sqlite3.connect(path) as conn:
-        assert conn.execute("SELECT value FROM schema_meta WHERE key='schema_version'").fetchone()[0] == "16"
+        assert conn.execute("SELECT value FROM schema_meta WHERE key='schema_version'").fetchone()[0] == "15"
         assert conn.execute("SELECT id,month,basis_date,status,version,memo,approved_by,closed_by FROM monthly_settlement").fetchall() == before
         assert "latest_run_id" not in {row[1] for row in conn.execute("PRAGMA table_info(monthly_settlement)")}
         assert conn.execute("PRAGMA foreign_key_list(monthly_settlement)").fetchall() == []