nuvio-linux 0.1.21alpha-2

Upstream 0.1.21-alpha — unchanged. This is a packaging-metadata fix
release (pkgrel 2); no application changes.

The gap

AUR nuvio-linux-bin 0.1.21alpha-1 shipped without a package()
function. The PKGBUILD downloaded the release tarball and correctly
verified it (sha256 + GPG signature), then discarded the extracted tree —
so every AUR install produced a 0-file package (0.00 MiB installed).

The release package attached here was always complete: the v0.1.21-alpha-1
smoke test validated it directly. What was never validated was the AUR
repack path — that verification step is now part of the release checklist
(makepkg -f in the AUR clone, then confirm the built package is
non-empty before pushing).

Fixes in this release

• AUR nuvio-linux-bin — added the missing package() (copies the
  auto-extracted opt/ + usr/ trees into the package). Verified: 296
  entries, 235 MiB installed, desktop entry + icon present.
• All packages (nuvio-linux, -bin, -git) — dropped the
  libstdc++ dependency. It is not a vanilla-Arch package: gcc-libs
  provides the C++ runtime, and only CachyOS repos ship a package by that
  name — so dependency resolution failed on non-CachyOS systems.
• pkgrel bumped to 2 across all three so package managers pick up
  every change.

Verify

sha256sum -c SHA256SUMS.txt
sudo pacman-key --add nuvio-linux-gpg-key.asc
sudo pacman-key --lsign-key 9201A54A09675CBEBAD08647EDDA55C8236D6C88
sudo pacman -U nuvio-linux-0.1.21alpha-2-x86_64.pkg.tar.zst

AUR users: yay -S nuvio-linux-bin (now 0.1.21alpha-2) or build
nuvio-linux-git from upstream source.