Prompt steps take a caller-supplied time limit (X-8a)

Prompt steps called call_provider without a timeout, so every AI call was cut at its
300 s default whatever the caller allowed. Now:
- PromptStep has an optional `timeout` (seconds) in its YAML;
- a universal --provider-timeout (tool wrappers, `cmdforge run`, `run-once`) sets the
  caller's limit, carried in ProviderExecutionPolicy so nested tools get it too;
- precedence: --provider-timeout, then the step's timeout, then 300 (unchanged default).

Requested by Orchestrated Discussions, whose work phases need attempts longer than 300 s.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tests/test_runner.py

@@ -1256,3 +1256,35 @@ class TestProviderExecutionPolicies:
 
         assert success is False
         resolver.assert_not_called()
+
+
+class TestPromptStepTimeout:
+    """X-8a: the provider's time limit comes from the caller or the step, not a fixed 300 s."""
+
+    @patch('cmdforge.runner.call_provider')
+    def test_default_stays_300_seconds(self, mock_call):
+        mock_call.return_value = ProviderResult(text="ok", success=True)
+        execute_prompt_step(PromptStep(prompt="x", provider="claude", output_var="o", plain_text=True), {})
+        assert mock_call.call_args.kwargs["timeout"] == 300
+
+    @patch('cmdforge.runner.call_provider')
+    def test_step_timeout_is_used(self, mock_call):
+        mock_call.return_value = ProviderResult(text="ok", success=True)
+        step = PromptStep(prompt="x", provider="claude", output_var="o", plain_text=True, timeout=1800)
+        execute_prompt_step(step, {})
+        assert mock_call.call_args.kwargs["timeout"] == 1800
+
+    @patch('cmdforge.runner.call_provider')
+    def test_callers_provider_timeout_overrides_the_step(self, mock_call):
+        from cmdforge.providers import ProviderExecutionPolicy
+        mock_call.return_value = ProviderResult(text="ok", success=True)
+        step = PromptStep(prompt="x", provider="claude", output_var="o", plain_text=True, timeout=1800)
+        execute_prompt_step(step, {}, execution_policy=ProviderExecutionPolicy(provider_timeout=120))
+        assert mock_call.call_args.kwargs["timeout"] == 120
+
+    def test_step_timeout_round_trips_and_is_validated(self):
+        step = PromptStep.from_dict({"prompt": "x", "provider": "claude", "output_var": "o", "timeout": "900"})
+        assert step.timeout == 900 and step.to_dict()["timeout"] == 900
+        assert "timeout" not in PromptStep(prompt="x", provider="claude", output_var="o").to_dict()
+        with pytest.raises(ValueError):
+            PromptStep(prompt="x", provider="claude", output_var="o", timeout=0)