Log message:
shells/brush-shell: Update to v0.4.0

Some key highlights:

A meaningful step forward in bash compatibility.
Major bash language features are now implemented or substantially expanded,
e.g.: set -e, set -u, pipefail, failglob, the ERR trap, coprocesses, and a great \ 
deal more.
Improved robustness across edge cases.
Closed pipes, broken stdout, unusual file-descriptor states, non-UTF8 history files,
and platform corner cases are now handled gracefully.
A systematic audit also removed an entire class of avoidable failure modes.
Broader platform support. Using brush as a login shell on macOS is now supported,
Windows path handling is overhauled, FreeBSD, Android and 32-bit targets build \ 
cleanly again,
and wasm32-wasip2 is now exercised in CI.
A more capable interactive shell. Optional TOML config,
zsh-style preexec/precmd hooks, experimental terminal integration,
expanded readline-macro support, and many completion improvements.
API improvements and foundations for what's next. Scaffolding for
a winnow-based parser, a generic Shell<Extensions> for embedders,
an opt-in bundled-coreutils build, and serde features for both AST and shell state.
This work has required breaking changes to API surface, mostly to brush-core.
Some changes were also made to brush-parser's API but we expect migration for
parser-only consumers to be straightforward and relatively minimal.