fix(api): default event loop to asyncio + cancellation-safe commit — kills the CI segfault (#340)

* fix(api): default the event loop to asyncio + cancellation-safe commit

The recurring CI e2e segfault traced to uvloop: the harness's
uvicorn.run() auto-selected it while production's serve() path never
consulted Config.loop (stock asyncio, accidentally safe). Every launch
site now resolves ROBOCO_UVICORN_LOOP (default asyncio; uvloop opt-in),
and DbCommitMiddleware's commit-in-send can no longer be interrupted
mid-wire: on cancellation it gets a bounded grace to finish (committed
data survives the 504), else invalidate-and-reraise.

* feat(runtime): expected-stop breadcrumbs attribute container deaths

Two production exit-143s had no attributable source: every orchestrator
kill path now records a short reason breadcrumb, and the exit monitor
consumes it -- an expected stop logs its reason at info, a genuinely
unexpected one logs none_recorded plus docker-inspect diagnostics
(OOMKilled, timestamps) so the next mystery SIGTERM self-identifies.

---------

Co-authored-by: Renn F <rennf93@users.noreply.github.com>

tests/unit/runtime/test_intake_spawn.py

@@ -1040,7 +1040,7 @@ class TestSpawnIntakeShutdownNoOrphan:
         _wire_spawn_mocks(monkeypatch, orch, run_calls)
         removed: list[str] = []
 
-        async def _remove(name: str) -> None:
+        async def _remove(name: str, **_kw: Any) -> None:
             removed.append(name)
 
         async def _run(cmd: list[str]) -> str:
@@ -1097,7 +1097,7 @@ class TestSpawnIntakeShutdownNoOrphan:
         # _wire_spawn_mocks' _remove_container is a no-op; override to record.
         removed: list[str] = []
 
-        async def _remove(name: str) -> None:
+        async def _remove(name: str, **_kw: Any) -> None:
             removed.append(name)
 
         monkeypatch.setattr(orch, "_remove_container", _remove)