Complete the Git commands: Git Grep: Repository-Aware Search

Create a disposable repository with tracked files under `src/` and `docs/`. Commit content containing the same search term in multiple files. Then create a staged change, an untracked file, and an ignored file containing distinguishable variants of the term. Demonstrate with captured output: a normal working-tree search; a line-numbered, case-insensitive search limited to `src/`; an index search with `--cached`; a committed-tree search against `HEAD`; an untracked-file search with `--untracked`; and a filename-only search with `-l`. Your evidence must show which repository state each command searched and must not rely on an external recursive `grep` command.