update to sgeupdated pipeline v19

changes the concept of rebuilding

.gitea/workflows/sgeupdated.yml

@@ -28,11 +28,19 @@ jobs:
           script: |
             set -euo pipefail
             cd /home/ubuntu/sgeUpdated
+
+            # --- Save old commit SHA ---
+            OLD_SHA=$(git rev-parse HEAD || true)
+
+            # --- Update repo ---
             git fetch origin main
             git reset --hard origin/main
 
+            # --- Save new commit SHA ---
+            NEW_SHA=$(git rev-parse HEAD)
+
             echo "🔍 Detecting changes..."
-            CHANGED_FILES=$(git diff --name-only HEAD^ HEAD || true)
+            CHANGED_FILES=$(git diff --name-only $OLD_SHA $NEW_SHA || true)
             echo "Changed files: $CHANGED_FILES"
 
             # --- Skip deploy if no backend/frontend changes ---