Fix the new dependency check for pasted snippets

An AI gave you a working TypeScript snippet that imports axios, though your codebase uses the built-in fetch. Pasting it in adds a package to package.json that nobody chose. Your team's check lists every package a snippet would add that is not already approved.

An assistant wrote flag_new_dependencies(snippet_imports, approved_packages). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• snippet_imports: the import paths in the snippet, such as axios, lodash/merge, ./utils/http or node:fs.
• approved_packages: the package names your team has approved.
• Return the package names to flag, each once, sorted.

Rules the tests check:

• Ignore an empty import, and any import that starts with ./, ../ or node:. Those are your own files and Node built-ins.
• Find the package name of each other import:
  • If it starts with @, it is a scoped package: the name is everything before the second /, or the whole import if it has fewer than 2 /.
  • Otherwise the name is everything before the first /, or the whole import if it has no /.
• Ignore an import whose package name is empty.
• Flag a package name unless approved_packages contains exactly that name.
• Return each flagged name once, sorted as plain strings in ascending order.