fix: fallback to yarn install when node_modules hard-linking fails

Agent-Logs-Url: https://github.com/MobilityData/mobilitydatabase-web/sessions/b94c36ed-c130-4c94-b685-7e7ba5ecd4c9

Co-authored-by: Alessandro100 <18631060+Alessandro100@users.noreply.github.com>

Author: Copilot

scripts/new-worktree.sh

@@ -31,10 +31,13 @@ done
 # Fall back to yarn install if node_modules doesn't exist in main repo
 if [ -d "$MAIN_REPO/node_modules" ]; then
   echo "📦 Hard-linking node_modules..."
-  cp -rl "$MAIN_REPO/node_modules" "$WORKTREE_DIR/node_modules"
+  if ! cp -rl "$MAIN_REPO/node_modules" "$WORKTREE_DIR/node_modules"; then
+    echo "⚠️  Hard-linking node_modules failed, running yarn install..."
+    (cd "$WORKTREE_DIR" && yarn install)
+  fi
 else
   echo "📦 node_modules not found in main repo, running yarn install..."
-  cd $WORKTREE_DIR && yarn install
+  (cd "$WORKTREE_DIR" && yarn install)
 fi
 
 # Open in VSCode
@@ -45,4 +48,4 @@ else
 fi
 
 echo "✅ Worktree ready at $WORKTREE_DIR on branch $BRANCH"
- 
+