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/release-notes.md

@@ -12,3 +12,9 @@ virtual environment first (`python3 -m venv .venv && . .venv/bin/activate`).
 The source archive is the same tree a clone would have: unzip it and run
 `./start.sh` (Linux/macOS) or `start.bat` (Windows).  Direct SIMtrace2 capture
 on Linux additionally needs the attached `70-simtrace2-pysniff.rules` udev rule.
+
+**Runtime zip (Windows-friendly, no installer)** — `simtrace-analyser-*.zip`
+is the runtime tree only (packages, PWA, launchers, docs — no tests, no git):
+extract it anywhere and run `start.bat` (Windows) or `./start.sh`
+(Linux/macOS).  Python 3 has to be on `PATH`; `pip install pyusb` is only
+needed for direct SIMtrace2 capture.