chore(release): update AUR SSH setup to use base64 decoding

.gitea/workflows/release.yml

@@ -105,9 +105,9 @@ jobs:
           VERSION="${{ github.event.inputs.tag || github.ref_name }}"
           PKGVER="${VERSION#v}"
 
-          # Setup SSH for AUR (printf + tr strips Windows line endings that break libcrypto)
+          # Setup SSH for AUR (key is stored base64-encoded to avoid newline mangling in secrets)
           mkdir -p ~/.ssh
-          printf '%s\n' "$AUR_SSH_KEY" | tr -d '\r' > ~/.ssh/aur
+          echo "$AUR_SSH_KEY" | base64 -d > ~/.ssh/aur
           chmod 600 ~/.ssh/aur
           ssh-keyscan aur.archlinux.org >> ~/.ssh/known_hosts