Windows Desktop Client CI (#2)

Adds a windows container build and a windows client build.
Outstanding issues:
- I'm not sure if `workflow_dispatch` works. Based on [this PR](https://github.com/go-gitea/gitea/pull/28163) it seems like it should, but I don't see a button. It might only work after merging into the default branch.
- The windows build container is building dioxus from git HEAD because there is an unreleased bugfix we are depending on. We should revert this to a versioned release (maybe using `binstall`) once they cut 0.7.2

Reviewed-on: #2

.gitea/workflows/windows-container-build.yaml

@@ -0,0 +1,27 @@
+name: Build Mumble Web 2 release builder containers
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 4 * * *"
+
+jobs:
+  windows-release-builder-container-build:
+    runs-on: windows
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Log in to container registry
+        uses: docker/login-action@v3
+        with:
+          registry: git.ohea.xyz
+          username: ${{ secrets.CI_REGISTRY_USER }}
+          password: ${{ secrets.CI_REGISTRY_PASSWORD }}
+
+      - name: Build Windows image
+        shell: bash
+        run: |
+          docker pull "$(grep -m1 '^FROM' Dockerfile | awk '{print $2}')"
+          docker build -t git.ohea.xyz/mumble/mumble-web2/windows-release-builder:latest -f ./docker/windows-release-builder.Dockerfile .
+          docker push git.ohea.xyz/mumble/mumble-web2/windows-release-builder:latest