Update tests for steering capability and send-path routing

Test drift surfaced by rebasing onto main:

- client SDK agent fixture now expects supportsSteering: false (the steering feature adds this capability flag, schema-defaulted).

- permission-response fake AgentManager gains startAgentRun, since the shared startAgentRun helper now routes through AgentManager.startAgentRun (the steer-vs-replace-vs-stream dispatch) instead of calling streamAgent/replaceAgentRun directly.

packages/client/src/index.test.ts

@@ -152,6 +152,7 @@ function createAgent(input: Partial<PaseoAgent> = {}): PaseoAgent {
       supportsRewindBoth: false,
       supportsRewindConversation: false,
       supportsRewindFiles: false,
+      supportsSteering: false,
       supportsToolInvocations: true,
     },
     currentModeId: null,