Update GitHub PAT configuration and improve script exit handling

.devcontainer/library-scripts/load-env.sh

@@ -53,8 +53,18 @@ fi
 if [[ -n "${pat}" ]] && [[ "${#pat}" -gt 30 ]]; then
     export GITHUB_PERSONAL_ACCESS_TOKEN="${pat}"
     echo "GitHub Personal Access Token loaded successfully"
-    exit 0
+    # Use return instead of exit when script is sourced
+    if [[ "${BASH_SOURCE[0]}" != "${0}" ]]; then
+        return 0
+    else
+        exit 0
+    fi
 else
     echo >&2 "ERROR: Could not find valid GitHub Personal Access Token"
-    exit 1
+    # Use return instead of exit when script is sourced
+    if [[ "${BASH_SOURCE[0]}" != "${0}" ]]; then
+        return 1
+    else
+        exit 1
+    fi
 fi