fix(sse): absorb AbortError/request_signal_aborted in the client-abort crash guard (#12165)

OmniRoute's SSE teardown aborts in-flight legs with
`Error [AbortError]: request_signal_aborted` on client disconnects
(open-sse/utils/streamHandler.ts getClientAbortReason), and fetch/DOM
cancellation surfaces as AbortError with an abort-flavoured message.
isClientAbortError() only matched message 'aborted'/'Aborted' plus errno
codes, so these shapes fell through shouldSwallowUncaught() and were
re-thrown from the process-level uncaughtException/unhandledRejection
handlers — killing the whole server on a routine client disconnect
(observed as repeated exit-code-7 crashes with
'uncaughtException: Error [AbortError]: request_signal_aborted').

Match AbortError by name when the message is abort-flavoured; genuine
errors that merely mention 'abort' (e.g. TypeError) still crash loudly.

Tests: new unit cases for the SSE/DOM AbortError shapes, a child-process
regression proving the process survives both benign emissions with the
production no-logger install shape, and a child-process test proving
genuine errors keep crash semantics.

src/shared/utils/httpClientAbortGuard.mjs

@@ -42,6 +42,13 @@ export function isClientAbortError(err) {
   const e = /** @type {NodeJS.ErrnoException} */ (err);
   // Node emits `Error: aborted` (no code) from http.Server#abortIncoming.
   if (e.message === "aborted" || e.message === "Aborted") return true;
+  // OmniRoute's SSE teardown aborts in-flight legs with
+  // `Error [AbortError]: request_signal_aborted` on client disconnects
+  // (open-sse/utils/streamHandler.ts), and fetch/DOM cancellation surfaces as
+  // `AbortError` with an abort-flavoured message. Same benign class as
+  // `Error: aborted` — an emitter-left 'error' event on any of these used to
+  // kill the process (#fix-dev-server-aborted).
+  if (e.name === "AbortError" && /abort/i.test(String(e.message))) return true;
   switch (e.code) {
     case "ERR_STREAM_PREMATURE_CLOSE":
     case "ECONNRESET":