feat(workflows): implement timeout for pacman installation

This update introduces a timeout mechanism for the pacman installation process in the app builder workflow. If the installation does not complete within 30 minutes, it will terminate and log a timeout message, improving the robustness of the build process.

- Adds a timeout for the pacman command to prevent indefinite hangs
- Implements a heartbeat to monitor the installation progress
- Provides clear error messages for timeout and failure scenarios

.gitea/workflows/app_builder.yaml

@@ -160,10 +160,34 @@ jobs:
 
           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
+            timeout --signal=TERM 30m \
+              pacman -Syu --needed --noconfirm --noprogressbar \
+              "${ARCH_PACKAGES[@]}" \
+              </dev/null &
+            ARCH_PACMAN_PID=$!
+            (
+              ARCH_WAIT_SECONDS=0
+              while true; do
+                sleep 30
+                ((ARCH_WAIT_SECONDS += 30))
+                echo "pacman is still running (${ARCH_WAIT_SECONDS}s elapsed)"
+              done
+            ) &
+            ARCH_HEARTBEAT_PID=$!
+
+            ARCH_PACMAN_STATUS=0
+            wait "$ARCH_PACMAN_PID" || ARCH_PACMAN_STATUS=$?
+            kill "$ARCH_HEARTBEAT_PID" 2>/dev/null || true
+            wait "$ARCH_HEARTBEAT_PID" 2>/dev/null || true
+
+            if [ "$ARCH_PACMAN_STATUS" -eq 0 ]; then
               break
             fi
 
+            if [ "$ARCH_PACMAN_STATUS" -eq 124 ]; then
+              echo "pacman attempt timed out after 30 minutes" >&2
+            fi
+
             if [ "$ARCH_INSTALL_ATTEMPT" -eq 3 ]; then
               echo "pacman failed after 3 attempts" >&2
               exit 1