## Why
Topology-neutral app-server integration tests should exercise automatic
environment selection so the same setup covers local and remote
executors.
## What
Migrate eligible tests to `TestAppServer::new_with_auto_env()` and
`send_thread_start_request_with_auto_env()`. Leave explicit-topology
tests unchanged, and skip the request-permissions case on Windows with a
TODO for cross-platform tool routing.
## Validation
- `just test -p codex-app-server`
- `bazel test //codex-rs/app-server:app-server-all-wine-exec-test
--test_output=errors`
Stacked on #29788.
## Why
Clients can archive and unarchive threads today, but there is no
app-server API for permanently removing a thread. Deletion also needs to
cover the full session tree: deleting a main thread should remove
spawned subagent threads and the related local metadata instead of
leaving orphaned rollout files, goals, or subagent state behind.
## What
- Adds the v2 `thread/delete` request and `thread/deleted` notification,
with the response shape kept consistent with `thread/archive`.
- Implements local hard delete for active and archived rollout files.
- Deletes the requested thread's state DB row as the commit point, then
best-effort cleans associated state including spawned descendants,
goals, spawn edges, logs, dynamic tools, and agent job assignments.
- Updates app-server API docs and generated protocol schema/TypeScript
fixtures.
