Execute a shell command. Commands run from the workspace directory. Use when a task needs a command-line operation that is not better handled by read, edit or search. Output is filtered: 1MB hard truncation; generic output shows first/last ~10 lines (max 200) with long lines (>500 chars) shortened; JSON output is replaced with a summary preview; `cargo test` hides passing tests, showing only failures + summary; stderr on success only shows `warning:` and error lines. Large output spills to a temp file with a `[view with: read <path>]` hint — use `read` on that path for full unfiltered output.