test(ocr): assert entrypoint.sh exit code in test_entrypoint_creates_tmpdir

A silent non-zero exit would previously cause the test to pass incorrectly
because only directory creation was checked. Exit code is now the first
assertion, catching regressions before the filesystem check runs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ocr-service/test_tmpdir.py

@@ -54,6 +54,10 @@ def test_entrypoint_creates_tmpdir(tmp_path):
         capture_output=True,
         text=True,
     )
+    assert result.returncode == 0, (
+        f"entrypoint.sh exited {result.returncode}\n"
+        f"stdout: {result.stdout}\nstderr: {result.stderr}"
+    )
     assert custom_tmp.exists(), (
         f"entrypoint.sh did not create TMPDIR={custom_tmp}\n"
         f"stdout: {result.stdout}\nstderr: {result.stderr}"