chore: stage changes before history rewrite

scripts/migrate_system_config.py

@@ -0,0 +1,24 @@
+"""Migrate: create system_config table."""
+import sqlite3
+from pathlib import Path
+
+DB_PATH = Path(__file__).parent.parent / "postcard.db"
+
+conn = sqlite3.connect(str(DB_PATH))
+cur = conn.cursor()
+
+cur.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='system_config'")
+if not cur.fetchone():
+    cur.execute(
+        "CREATE TABLE system_config ("
+        "key TEXT PRIMARY KEY, "
+        "value TEXT NOT NULL DEFAULT '', "
+        "updated_at TIMESTAMP"
+        ")"
+    )
+    conn.commit()
+    print("OK: system_config table created")
+else:
+    print("SKIP: system_config table exists")
+
+conn.close()