## Summary
- add the exec-server working directory to `environment/info` as an
optional `PathUri`
- populate it from the executor process's current directory
- preserve compatibility with older responses that omit `cwd`
## Why
Remote clients currently have no executor-native default working
directory. This forces callers such as app-server-backend to assume
`/workspace`, which fails for laptop environments. Reporting the cwd
alongside the detected shell lets clients use the path convention and
location of the actual executor.
## Impact
This is backward-compatible: the new response field is optional, and
clients can continue handling responses from older exec servers. A
follow-up app-server-backend change will consume the value for cwd-less
`command/exec` requests.
## Validation
- `just test -p codex-exec-server` (275 passed, 2 skipped)
Rasmus Rygaard
66f0220c56