SearchFilesTool

Recursively searches for files and directories whose name contains a case-insensitive substring, sandboxed to external storage via PathValidator (defaults to /sdcard). Recursion is capped at depth 5; unreadable directories are skipped silently. Requires READ_EXTERNAL_STORAGE on API ≤32; uses File API access on API 33+. Output: query, search_path, results (each {name, path, size_bytes, last_modified, is_directory}) capped at the limit param, and count.