Reject queued /reserve immediately on busy null workers

A held reservation runs for up to MAX_RESERVATION_SECONDS (default 1h), so
queueing a second /reserve behind it makes no sense — the wait would dwarf
any sane timeout. Set max_queue_time=0.0 so the framework rejects 429 as
soon as another reservation is in flight, and serverless routes the request
to a free worker or scales a new one up.

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

workers/null/worker.py

@@ -159,7 +159,12 @@ worker_config = WorkerConfig(
         HandlerConfig(
             route="/reserve",
             allow_parallel_requests=False,
-            max_queue_time=30.0,
+            # Reject (429) any /reserve that arrives while the worker is
+            # already busy. A held reservation lasts up to MAX_RESERVATION_
+            # SECONDS, so queueing behind it would mean hours of wait —
+            # better to bounce the request immediately so serverless routes
+            # it to a free worker (or spins up a new one).
+            max_queue_time=0.0,
             remote_function=reserve_worker,
             workload_calculator=lambda _payload: 100.0,
             benchmark_config=BenchmarkConfig(