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.

.github/workflows/pip.yml

@@ -9,7 +9,7 @@ on:
       - 'v*'
 
 env:
-  PYTHON_VERSION: 3.14
+  PYTHON_VERSION: "3.13"
 
 jobs:
   build:

.github/workflows/test.yml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         os: [ubuntu-22.04]
         # os: [ubuntu-22.04, macos-latest, windows-latest]
-        python: [3.14]
+        python: ["3.13"]
 
     steps:
       - uses: actions/checkout@v4
@@ -38,7 +38,7 @@ jobs:
       - name: Setup PDM
         uses: pdm-project/setup-pdm@v3
         with:
-          python-version: '3.14'
+          python-version: '3.13'
           cache: true
 
       ### Install Python & JS Dependencies