feat: add database backup and restore in system settings

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_backup.py

@@ -0,0 +1,46 @@
+from pathlib import Path
+
+import pytest
+
+from packages.db.backup import (
+    backup_db,
+    is_valid_backup_name,
+    list_backups,
+    resolve_backup_file,
+    restore_db,
+)
+
+
+def test_backup_roundtrip(tmp_path: Path):
+    db = tmp_path / "live.db"
+    backup_dir = tmp_path / "backups"
+    conn = __import__("sqlite3").connect(str(db))
+    conn.execute("CREATE TABLE t (id INTEGER PRIMARY KEY, v TEXT)")
+    conn.execute("INSERT INTO t(v) VALUES ('hello')")
+    conn.commit()
+    conn.close()
+
+    dest = backup_db(db, backup_dir, tz="UTC")
+    assert dest.is_file()
+    assert is_valid_backup_name(dest.name)
+
+    conn = __import__("sqlite3").connect(str(db))
+    conn.execute("DELETE FROM t")
+    conn.commit()
+    conn.close()
+
+    restore_db(dest, db)
+    conn = __import__("sqlite3").connect(str(db))
+    row = conn.execute("SELECT v FROM t").fetchone()
+    conn.close()
+    assert row[0] == "hello"
+
+    items = list_backups(backup_dir)
+    assert len(items) == 1
+    assert items[0]["name"] == dest.name
+    assert resolve_backup_file(backup_dir, dest.name) == dest.resolve()
+
+
+def test_invalid_backup_name(tmp_path: Path):
+    with pytest.raises(ValueError):
+        resolve_backup_file(tmp_path, "../etc/passwd")