fix: run the read-only tools from the repo root

Only verify.py and generate_pack.py moved to the repository root. From
any other folder slots, region_audit, provenance_report and bundled_only
said database.json was missing and to rebuild it, identity and
list_platforms named a missing folder, and game_rules ended on a
FileNotFoundError traceback. work_from_repo_root moves to common.py and
the eight tools call it: defaults are read from the root, a path the
user typed from where it was typed.

scripts/slots.py

@@ -1009,6 +1009,9 @@ def main() -> int:
         "without it the run reports them and exits 0",
     )
     args = parser.parse_args()
+    from common import work_from_repo_root  # noqa: PLC0415
+
+    work_from_repo_root(args, parser, ["db", "platforms_dir", "emulators_dir"])
 
     import contextlib