ci: add vulkan-headers for Qt6, fix install SIGPIPE issue

Author: zccrs

.github/workflows/dtkdeclarative-archlinux-build.yml

@@ -52,6 +52,7 @@ jobs:
             librsvg libraw \
             libqtxdg \
             icu uchardet dbus spdlog gsettings-qt \
+            vulkan-headers \
             dtkcommon dtk6log \
             treeland-protocols dtk6core dtk6gui
 
@@ -103,19 +104,13 @@ jobs:
 
       - name: Install dtkdeclarative to staging directory
         run: |
-          set -o pipefail
-          DESTDIR=/tmp/dtkdeclarative-install cmake --install build --verbose 2>&1 | tee /tmp/cmake-install.log
+          DESTDIR=/tmp/dtkdeclarative-install cmake --install build
           echo "Total: $(find /tmp/dtkdeclarative-install -type f | wc -l) files"
           find /tmp/dtkdeclarative-install -type f | head -20
 
       - name: Print install log on failure
         if: failure()
-        run: |
-          echo "=== cmake-install.log (last 80 lines) ==="
-          tail -80 /tmp/cmake-install.log 2>/dev/null || echo "(not found)"
-          tail -20 /tmp/cmake-install.log 2>/dev/null | while IFS= read -r line; do
-            echo "::error::$line"
-          done
+        run: echo "::error::Install step failed — check the step output above"
 
       - name: Create installation package
         run: |