v1.0.1

Add CI to build & publish Windows exe on version tags

Previously the Windows .exe was built by hand (build_exe.bat) and shared
ad-hoc, so stale builds (missing newer features like the Clear NVS
button) ended up in the field.

- Add .github/workflows/build-exe.yml: builds the exe on a Windows
  runner and attaches it to a GitHub Release when a v* tag is pushed
  (also produces a downloadable artifact on manual dispatch).
- Point the README Windows download link at releases/latest.
- Fix the stale `pyinstaller main.spec` reference (no such spec exists;
  the build uses build_exe.bat / the new workflow).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ToGHcVpwGCWn5AHGmdtDH5