workflows: Add Windows build.

Fixes #1070.
Closes #1350.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Author: andersk

.github/workflows/node.js.yml

@@ -8,7 +8,10 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/setup-node@v6
         with:

README.md

@@ -1,7 +1,6 @@
 # Zulip Desktop Client
 
 [![Build Status](https://github.com/zulip/zulip-desktop/actions/workflows/node.js.yml/badge.svg)](https://github.com/zulip/zulip-desktop/actions/workflows/node.js.yml?query=branch%3Amain)
-[![Windows Build Status](https://ci.appveyor.com/api/projects/status/github/zulip/zulip-desktop?branch=main&svg=true)](https://ci.appveyor.com/project/zulip/zulip-desktop/branch/main)
 [![XO code style](https://img.shields.io/badge/code_style-XO-5ed9c7.svg)](https://github.com/sindresorhus/xo)
 [![project chat](https://img.shields.io/badge/zulip-join_chat-brightgreen.svg)](https://chat.zulip.org)