Implement tag matcher and filesystem

This interview reportedly included two coding problems: 1. **Tag matching in text** Given a sentence and a list of tags or keywords, return the tags that appear in the sentence as **whole-word matches**. Matching may be treated as case-insensitive, but partial-word matches do **not** count. For example, if the sentence contains `blueprint`, the tag `blue` must **not** be considered a match. Be prepared to clarify how punctuation, duplicates, and output ordering should be handled. 2. **In-memory file system** Design and implement an in-memory file system that supports common operations such as: - creating directories, - listing directory contents, - writing file contents, - reading file contents. Be prepared to discuss path parsing, internal data structures, and edge cases such as nested directories, creating missing parents, and appending to an existing file.