ci: add failure log printing step for debugging

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: zccrs

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

@@ -78,9 +78,16 @@ jobs:
           echo "=== Built files ==="
           find build -name "*.so" -o -name "*.a" | head -20
 
+      - name: Print build logs on failure
+        if: failure()
+        run: |
+          echo "=== cmake-configure.log ==="
+          cat /tmp/cmake-configure.log 2>/dev/null || echo "(not found)"
+          echo "=== cmake-build.log (last 100 lines) ==="
+          tail -100 /tmp/cmake-build.log 2>/dev/null || echo "(not found)"
+
       - name: Install dtkdeclarative to staging directory
         run: |
-          cat build/cmake_install.cmake 2>/dev/null | head -30 || true
           DESTDIR=/tmp/dtkdeclarative-install cmake --install build --verbose
           echo "Total: $(find /tmp/dtkdeclarative-install -type f | wc -l) files"
           find /tmp/dtkdeclarative-install -type f | head -20