test: pin sandbox to the volume's region

Even with retries and the post-list sleep, the sandbox-side volume
lookup was returning 404 deterministically (6/6 attempts, ~30s apart).
The volume is created in `ord` but the sandbox create call didn't
specify a region, so it landed in a different cluster that doesn't
know about the volume. Pin the sandbox create to `--region ord` to
match the volume's region.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: crowlbot

tests/sandbox.test.ts

@@ -188,6 +188,8 @@ Deno.test("sandbox with volume mount", async () => {
         "--quiet",
         "--timeout",
         "60s",
+        "--region",
+        "ord",
         "--volume",
         `${volumeId}:/data/dataset`,
       );