## Summary
- make bubblewrap the default Linux sandbox and keep
`use_legacy_landlock` as the only override
- remove `use_linux_sandbox_bwrap` from feature, config, schema, and
docs surfaces
- update Linux sandbox selection, CLI/config plumbing, and related
tests/docs to match the new default
- fold in the follow-up CI fixes for request-permissions responses and
Linux read-only sandbox error text
## Summary
- stop reserving a localhost port in the websocket tests before spawning
the server
- let the app-server bind `127.0.0.1:0` itself and read back the actual
bound websocket address from stderr
- update the websocket test helpers and callers to use the discovered
address
## Why this fixes the flake
The previous harness reserved a port in the test process, dropped it,
and then asked the server process to bind that same address. On busy
runners there is a race between releasing the reservation and the child
process rebinding it, which can produce sporadic startup failures.
Binding to port `0` inside the server removes that race entirely, and
waiting for the server to report the real bound address makes the tests
connect only after the listener is actually ready.
* Add an ability to stream stdin, stdout, and stderr
* Streaming of stdout and stderr has a configurable cap for total amount
of transmitted bytes (with an ability to disable it)
* Add support for overriding environment variables
* Add an ability to terminate running applications (using
`command/exec/terminate`)
* Add TTY/PTY support, with an ability to resize the terminal (using
`command/exec/resize`)
