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>

docs/ARCHITECTURE.md

@@ -547,7 +547,9 @@ with rollback on failure (writing the running executable fails with ETXTBSY;
 rename works). A packaged install is detected by `data/` and `lib/` next to
 the binary; anything else exits with "update manually". A manifest whose
 protocol is newer than the local one is a required update. Windows apply
-(`*.old` rename, swept on next start) exists but is untested. The version is
+renames in-use files to `*.old` (swept on next start); CI tests it against a
+running exe on NTFS. The manifest's `assets` maps `linux-x64` /
+`windows-x64` to archive URLs; top-level `url` (Linux) is for builds <= 0.2.1. The version is
 stamped with `--dart-define=APP_VERSION` (dev runs report `0.0.0-dev` and skip
 checks). `watch_together --upgrade` (or the shipped `update.sh`) runs it from
 the CLI; `UpdateController` runs the same code for Home's update indicator,

docs/DEVELOPMENT.md

@@ -12,6 +12,7 @@ mpv libraries come from `media_kit_libs_video`.
 cd apps/desktop && flutter pub get && flutter run -d linux
 cd apps/desktop && flutter build linux --release --dart-define=APP_VERSION=<x.y.z>
 tool/package_linux.sh [--skip-build] [--noupload]    # dist/*.tar.gz
+powershell -File tool/package_windows.ps1 [-SkipBuild]  # dist/*.zip (on Windows)
 cd packages/server && dart compile exe bin/server.dart -o watch-together-server
 ```
 
@@ -77,12 +78,16 @@ User pushes tags; CI does the rest.
 
 1. `tool/release.sh [patch|minor|major] [--dry-run]`: derives the next
    version from the latest tag, bumps the three pubspecs in lockstep, writes
-   `updates/manifest.json` (asset URL is predictable), commits `Release vX.Y.Z`,
+   `updates/manifest.json` (per-platform `assets` URLs are predictable; `url`
+   stays the Linux tarball for builds <= 0.2.1), commits `Release vX.Y.Z`,
    makes an annotated tag.
 2. Review, then `git push --follow-tags`.
-3. `.gitea/workflows/release.yml` builds the Linux tarball and runs
-   `tool/release_publish.sh vX.Y.Z`, which creates the release and uploads it.
-   By hand: `tool/package_linux.sh` then `tool/release_publish.sh vX.Y.Z`.
+3. `.gitea/workflows/release.yml` runs one job per platform: Linux builds
+   with `tool/package_linux.sh`, Windows (runner `yuuka-windows`, host mode,
+   PowerShell only) with `tool/package_windows.ps1`. Each then runs
+   `dart tool/release_publish.dart vX.Y.Z <archive>`, which creates the
+   release if the other job hasn't yet and uploads (or replaces) its asset.
+   By hand: package, then the same `dart tool/release_publish.dart` line.
 
 Tokens come from the environment (`RELEASE_TOKEN`, or Actions-provided
 `GITHUB_TOKEN`/`GITEA_TOKEN`). The manifest has no `sha256` by default; the

docs/ROADMAP.md

@@ -6,13 +6,12 @@ off by deleting it in the same commit as the code. Wire changes also edit
 
 ## Backlog
 
-1. **Windows build + CI.** There is no Windows runner. Try
-   `ubuntu2610/flutter_build` (LLVM-MinGW + Wine `gen_snapshot`) on the Linux
-   runner, fallback a GitHub Actions mirror. The manifest needs per-platform
-   URLs and `release_publish.sh` must handle a second platform. The updater's
-   Windows apply path exists but is untested. The tarball's
-   `watch-together-server` needs a Windows `dart compile exe` too. Desktop
-   tests are not in CI either.
+1. **Windows: first real install.** CI builds and publishes
+   `watch-together-<ver>-windows-x64.zip` (libmpv bundled) and runs the
+   updater tests on NTFS, but nobody has launched the app on Windows yet.
+   Check: playback, fullscreen controls, hosting (firewall prompt), in-app
+   update from one release to the next. The rest of the desktop tests are
+   not in CI.
 
 2. **Jellyfin** (epic, below).