fix(workflow): improve Arch Linux package installation process

The workflow for building and publishing to Arch Linux has been updated to
enhance the package installation process. This includes adding multiple
mirror sources to ensure reliability and implementing retry logic for
package installation attempts.

- Removed dependency on the Windows publish job
- Added backup mirrors for Arch Linux package management
- Implemented retry logic for package installation failures

.gitea/workflows/app_builder.yaml

@@ -122,7 +122,6 @@ jobs:
 
   publish-arch:
     name: Build and publish gitty-desktop to AUR
-    needs: publish-windows
     runs-on: archlinux
     environment: production
     env:
@@ -136,11 +135,42 @@ jobs:
       - name: Prepare Arch job container
         working-directory: /
         run: |
-          pacman -Syu --noconfirm
-          pacman -S --needed --noconfirm \
-            base-devel curl git nodejs npm openssh rust \
-            webkit2gtk-4.1 gtk3 hicolor-icon-theme \
+          set -euo pipefail
+
+          # The runner image may contain only a single geo mirror. Seed several
+          # currently active HTTPS mirrors and retain the image's list as a
+          # fallback so one slow CDN cannot fail the complete release.
+          ARCH_MIRROR_BACKUP="$(mktemp)"
+          cp /etc/pacman.d/mirrorlist "$ARCH_MIRROR_BACKUP"
+          printf '%s\n' \
+            'Server = https://frankfurt.mirror.pkgbuild.com/$repo/os/$arch' \
+            'Server = https://mirror.osbeck.com/archlinux/$repo/os/$arch' \
+            'Server = https://mirror.ubrco.de/archlinux/$repo/os/$arch' \
+            'Server = https://ftp.halifax.rwth-aachen.de/archlinux/$repo/os/$arch' \
+            'Server = https://geo.mirror.pkgbuild.com/$repo/os/$arch' \
+            > /etc/pacman.d/mirrorlist
+          sed -n '/^[[:space:]]*Server[[:space:]]*=/p' "$ARCH_MIRROR_BACKUP" \
+            >> /etc/pacman.d/mirrorlist
+
+          ARCH_PACKAGES=(
+            base-devel curl git nodejs npm openssh rust
+            webkit2gtk-4.1 gtk3 hicolor-icon-theme
             libappindicator-gtk3 librsvg xdotool
+          )
+
+          for ARCH_INSTALL_ATTEMPT in 1 2 3; do
+            echo "pacman attempt $ARCH_INSTALL_ATTEMPT of 3"
+            if pacman -Syu --needed --noconfirm "${ARCH_PACKAGES[@]}"; then
+              break
+            fi
+
+            if [ "$ARCH_INSTALL_ATTEMPT" -eq 3 ]; then
+              echo "pacman failed after 3 attempts" >&2
+              exit 1
+            fi
+
+            sleep "$((ARCH_INSTALL_ATTEMPT * 5))"
+          done
 
       - uses: actions/checkout@v5
         with:
@@ -219,7 +249,6 @@ jobs:
 
   publish-ubuntu:
     name: Build and publish Ubuntu AppImage
-    needs: publish-arch
     permissions:
       contents: write
     environment: production