Session::execute (the entry point of the UI, CLI, control channel and
MCP) runs each command through lightcraft_engine::guard::catch: a panic
that escapes a command becomes that command's error (EngineError::Other,
shown like any failed command) and the session, catalog and undo history
stay usable. The desktop app installs guard::install_hook, which keeps
the default stderr report and appends the panic location and message to
<temp>/lightcraft-panics.log.
The desktop app crate (already clean) now #![deny]s unwrap/expect/panic/
unimplemented/todo/unreachable; clippy.toml as in the steering PR.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
