Release a Windows-friendly runtime zip (v2.7.12)

The releases carried the wheel and the sdist; the only zip was GitHub's source
archive of the whole repository (tests, CI, tools).  A Windows user just wants
to extract a folder and double-click start.bat.

- scripts/build_release_zip.py builds simtrace-analyser-<version>.zip with a
  single top-level directory: the two Python packages, the PWA runtime files
  (frontend/tests and package.json stay out), the four launchers, the udev
  rule, the READMEs and the screenshot.  The .bat entries are written with
  CRLF line endings (cmd.exe mishandles bare-LF labels/goto), the .sh files
  keep their executable bit; LICENSE is included automatically once the repo
  has one.
- tests/test_release_zip.py pins the archive shape, the exclusions, the sw.js
  PRECACHE drift (every precached asset must travel), the CRLF/LF line endings
  and start.sh's mode.
- the release workflow builds the zip, checks it carries start.bat and the
  PWA, uploads it with the run and attaches it to the release.
- READMEs (EN/RU) and the release-notes template offer the zip as the
  Windows-friendly option; version 2.7.12, PWA cache v94.

Verified: the built zip (34 entries, 658 KB compressed) extracted and started
on Linux serves the same index.html; 553 Python + 80 Node tests.

.github/workflows/release.yml

@@ -49,6 +49,22 @@ jobs:
       - name: Build the sdist and the wheel
         run: python -m build --sdist --wheel
 
+      - name: Build the runtime zip
+        run: python scripts/build_release_zip.py --output dist
+
+      - name: The runtime zip is complete
+        run: |
+          python - <<'PY'
+          import glob
+          import zipfile
+          archive = glob.glob('dist/*.zip')[0]
+          names = zipfile.ZipFile(archive).namelist()
+          for required in ('start.bat', 'frontend/index.html'):
+              assert any(n.endswith('/' + required) for n in names), \
+                  '%s is missing from %s' % (required, archive)
+          print('%s: %d entries, launchers and PWA bundled' % (archive, len(names)))
+          PY
+
       - name: The wheel bundles the PWA
         run: |
           python - <<'PY'
@@ -96,4 +112,4 @@ jobs:
             --title "$GITHUB_REF_NAME" \
             --generate-notes \
             --notes-file .github/release-notes.md \
-            dist/*.whl dist/*.tar.gz 70-simtrace2-pysniff.rules
+            dist/*.whl dist/*.tar.gz dist/*.zip 70-simtrace2-pysniff.rules