feat(server): re-export URL helpers; callable job done_message

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

tests/test_jobs.py

@@ -51,5 +51,13 @@ def test_eviction_keeps_within_cap():
     jobs.JOBS.clear()
 
 
+def test_run_job_callable_done_message():
+    job = jobs.create_job(hit={}, message="m")
+    jobs.run_job(job.id, lambda: {"ok": 2, "total": 3},
+                 done_message=lambda res: f"{res['ok']}/{res['total']} done")
+    j = _wait(job.id, "done")
+    assert j.message == "2/3 done"
+
+
 def teardown_module():
     jobs.JOBS.clear()