fix: allow tool_choice, parallel_tool_calls, prompt_cache_key in codex preflight

_preflight_codex_api_kwargs rejected these three fields as unsupported,
but _build_api_kwargs adds them to every codex request. This caused a
ValueError before _interruptible_api_call was reached, which was caught
by the retry loop and retried with exponential backoff — appearing as
an infinite hang in tests (275s total backoff across 6 retries).

The fix adds these keys to allowed_keys and passes them through to the
normalized request dict.

This fixes the hanging test_cron_run_job_codex_path_handles_internal_401_refresh
test (now passes in 2.6s instead of timing out).

run_agent.py

@@ -1781,6 +1781,7 @@ class AIAgent:
         allowed_keys = {
             "model", "instructions", "input", "tools", "store",
             "reasoning", "include", "max_output_tokens", "temperature",
+            "tool_choice", "parallel_tool_calls", "prompt_cache_key",
         }
         normalized: Dict[str, Any] = {
             "model": model,
@@ -1806,6 +1807,12 @@ class AIAgent:
         if isinstance(temperature, (int, float)):
             normalized["temperature"] = float(temperature)
 
+        # Pass through tool_choice, parallel_tool_calls, prompt_cache_key
+        for passthrough_key in ("tool_choice", "parallel_tool_calls", "prompt_cache_key"):
+            val = api_kwargs.get(passthrough_key)
+            if val is not None:
+                normalized[passthrough_key] = val
+
         if allow_stream:
             stream = api_kwargs.get("stream")
             if stream is not None and stream is not True: