Add Python 3.13 support with uuid7 backport compatibility

- Create uuid_compat.py module that provides uuid7 for Python <3.14
  using uuid_extensions package, and native uuid.uuid7 for Python 3.14+
- Update all model files and migrations to use archivebox.uuid_compat
- Add uuid7 conditional dependency in pyproject.toml for Python <3.14
- Update requires-python to >=3.13 (from >=3.14)
- Update GitHub workflows, lock_pkgs.sh to use Python 3.13
- Update tool configs (ruff, pyright, uv) for Python 3.13

This enables running ArchiveBox on Python 3.13 while maintaining
forward compatibility with Python 3.14's native uuid7 support.

archivebox/base_models/models.py

@@ -5,7 +5,8 @@ __package__ = 'archivebox.base_models'
 import io
 import csv
 import json
-from uuid import uuid7, UUID
+from uuid import UUID
+from archivebox.uuid_compat import uuid7
 from typing import Any, Iterable, ClassVar
 from pathlib import Path