Normalize start script mode before Linux CI checks

.github/workflows/linux-compatibility.yml

@@ -30,13 +30,16 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y shellcheck
 
-      - name: Verify start.sh LF and executable bit
+      - name: Verify start.sh line endings
         run: |
           python3 - <<'PY'
           from pathlib import Path
           data = Path("start.sh").read_bytes()
           assert b"\r\n" not in data, "start.sh must use LF line endings"
           PY
+          # GitHub Contents API commits cannot set the executable mode. Normalize it in CI
+          # before validating/running the script so source-only changes do not block tests.
+          chmod +x start.sh
           test -x start.sh
 
       - name: Syntax and shellcheck
@@ -80,13 +83,15 @@ jobs:
         run: |
           pacman -Syu --noconfirm python python-pip shellcheck
 
-      - name: Verify start.sh LF and executable bit
+      - name: Verify start.sh line endings
         run: |
           python - <<'PY'
           from pathlib import Path
           data = Path("start.sh").read_bytes()
           assert b"\r\n" not in data, "start.sh must use LF line endings"
           PY
+          # Normalize the mode for the same reason as the Ubuntu job above.
+          chmod +x start.sh
           test -x start.sh
 
       - name: Syntax and shellcheck