Windows: shippable cross-compiled .zip + console fix + release CI

The tree already links a working x86_64-pc-windows-gnu exe; turn that into
a shipped artifact:

- scripts/package.sh gains a `win` target (and `all` picks it up when the
  mingw toolchain is present) that cross-compiles and zips the exe +
  LICENSE + a README listing the yt-dlp/ffmpeg/mpv PATH deps.
- Forgejo release workflow installs mingw-w64 + zip + the rust target, so
  a tag push produces yt-offline-<ver>-x86_64-windows.zip from the same
  Linux container — no Windows runner needed.
- main.rs: attach_windows_console() (cfg(windows), windows-sys
  AttachConsole) reattaches a release build to the launching terminal so
  --web/CLI output is visible, while a double-click stays windowless
  (release sets windows_subsystem = "windows").
- ROADMAP 3.1 updated: Windows ships; macOS deferred (needs a Mac runner).

Native Linux build + 128 unit / 11 integration tests still green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.forgejo/workflows/release.yml

@@ -31,12 +31,19 @@ jobs:
         # libxcb + friends are needed to *link* the eframe/winit GUI even
         # in headless CI. curl + file are used by the packaging script and
         # appimagetool. rpm provides rpmbuild for cargo-generate-rpm's
-        # payload assembly on a Debian host.
+        # payload assembly on a Debian host. mingw-w64 + zip let the same
+        # script cross-compile the Windows .zip from this Linux container.
         run: |
           apt-get update
           apt-get install -y --no-install-recommends \
             libxcb1-dev libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev \
-            curl file rpm ca-certificates
+            curl file rpm ca-certificates mingw-w64 zip
+
+      - name: Add Windows cross-compile target
+        # package.sh's `all` only builds the Windows zip when this target +
+        # mingw + zip are all present (win_available), so this step is what
+        # opts the release build into producing yt-offline-*-x86_64-windows.zip.
+        run: rustup target add x86_64-pc-windows-gnu
 
       - name: Cache cargo registry + build
         uses: actions/cache@v4
@@ -80,5 +87,7 @@ jobs:
             - `.deb` — Debian / Ubuntu / Mint
             - `.rpm` — Fedora / RHEL / openSUSE
             - `.AppImage` — any Linux (chmod +x and run)
+            - `-x86_64-windows.zip` — Windows 10/11 (unzip, run yt-offline.exe)
 
-            Runtime requirements: yt-dlp, ffmpeg, mpv, xdg-utils on PATH.
+            Runtime requirements: yt-dlp, ffmpeg, mpv on PATH (plus
+            xdg-utils on Linux). The Windows zip's README lists the same.