fix(infra): bound macOS process start probes (#109064)

* fix(infra): bound macOS process start probes

* docs(changelog): note macOS process probe deadline

Co-authored-by: Alix-007 <li.long15@xydigit.com>

* test(infra): cover process probe timeout

---------

Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/shared/pid-alive.test.ts

@@ -165,14 +165,18 @@ describe("process start times", () => {
         expect.objectContaining({
           encoding: "utf8",
           env: expect.objectContaining({ LC_ALL: "C", TZ: "UTC" }),
+          timeout: 1000,
         }),
       );
     });
   });
 
-  it("returns null for unavailable Darwin file-lock start times", () => {
+  it("fails conservatively when the Darwin file-lock start-time probe times out", () => {
     vi.spyOn(childProcess, "execFileSync").mockImplementation(() => {
-      throw new Error("missing process");
+      throw Object.assign(new Error("spawnSync /bin/ps ETIMEDOUT"), {
+        code: "ETIMEDOUT",
+        signal: "SIGTERM",
+      });
     });
 
     return withMockedPlatform("darwin", async () => {

src/shared/pid-alive.ts

@@ -2,6 +2,8 @@
 import childProcess from "node:child_process";
 import fsSync from "node:fs";
 
+const DARWIN_PS_TIMEOUT_MS = 1000;
+
 function isValidPid(pid: number): boolean {
   return Number.isInteger(pid) && pid > 0;
 }
@@ -59,6 +61,7 @@ function getDarwinProcessStartTime(pid: number): number | null {
         encoding: "utf8",
         env: { ...process.env, LC_ALL: "C", TZ: "UTC" },
         stdio: ["ignore", "pipe", "ignore"],
+        timeout: DARWIN_PS_TIMEOUT_MS,
       })
       .trim();
     // Darwin's lstart output has no timezone. Force UTC for both ps and parsing so