CI: Windows build + release on yuuka-windows

tool/package_windows.ps1 builds watch-together-<ver>-windows-x64.zip
(same layout as the Linux tarball, libmpv bundled, update.bat and
watch-together-server.exe). The release workflow gets a windows job;
ci runs the updater tests on Windows. Publishing moves to
tool/release_publish.dart (dart: only, no python/bash on Windows), which
tolerates both jobs racing to create the release and replaces an asset
on re-runs. release.sh writes both asset URLs into the manifest.
Windows jobs check out with plain git (the host's cached
actions/checkout clone was corrupt).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -36,4 +36,42 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
           RELEASE_TOKEN: ${{ secrets.RELEASE_TOKEN }}
-        run: tool/release_publish.sh "${{ github.ref_name }}"
+        run: |
+          VER="${GITHUB_REF_NAME#v}"
+          dart tool/release_publish.dart "$GITHUB_REF_NAME" "dist/watch-together-$VER-linux-x64.tar.gz"
+
+  windows:
+    # yuuka-windows: host-mode runner (no containers), runs as SYSTEM, has
+    # git + VS 2022 Build Tools but no bash/python — PowerShell and Dart
+    # only. Checkout is plain git: that host's cached actions/checkout
+    # clone was corrupt, and no `uses:` means no action cache to rot.
+    runs-on: windows-latest
+    steps:
+      - name: Checkout
+        shell: powershell
+        run: |
+          git init -q .
+          git remote add origin "$env:GITHUB_SERVER_URL/$env:GITHUB_REPOSITORY.git"
+          git fetch -q --tags origin "$env:GITHUB_SHA"
+          if ($LASTEXITCODE) { exit 1 }
+          git checkout -q --force FETCH_HEAD
+
+      - name: Setup Flutter
+        shell: powershell
+        run: powershell -NoProfile -ExecutionPolicy Bypass -File tool/setup_flutter_windows.ps1
+
+      - name: Build zip
+        shell: powershell
+        run: powershell -NoProfile -ExecutionPolicy Bypass -File tool/package_windows.ps1
+
+      - name: Publish release
+        if: startsWith(github.ref, 'refs/tags/v')
+        shell: powershell
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          RELEASE_TOKEN: ${{ secrets.RELEASE_TOKEN }}
+        run: |
+          $Ver = $env:GITHUB_REF_NAME.TrimStart('v')
+          dart tool/release_publish.dart $env:GITHUB_REF_NAME "dist/watch-together-$Ver-windows-x64.zip"
+          if ($LASTEXITCODE) { exit 1 }