fix: restore permission config in background session creation

Add permission: [{ permission: 'question', action: 'deny', pattern: '*' }]
to client.session.create() call to prevent background sessions from
asking questions that go unanswered, causing hangs.

src/features/background-agent/task-starter.ts

@@ -69,7 +69,8 @@ export async function startQueuedTask(args: {
     body: {
       parentID: input.parentSessionID,
       title: `${input.description} (@${input.agent} subagent)`,
-    },
+      permission: [{ permission: "question", action: "deny" as const, pattern: "*" }],
+    } as any,
     query: {
       directory: parentDirectory,
     },