Search workspace file contents with ripgrep.

Usage:
- `pattern` is treated as a regular expression.
- `path` limits the search root and defaults to the workspace root.
- `include` narrows matches to files matching a glob such as `*.py`.
- Set `case_sensitive=true` only when exact casing matters.
- Use this tool to locate symbols, strings, or code patterns before reading files in detail.
- After finding matches, use `read` on the most relevant files for full context.
