Add session permission support to background agents for denying questions

Implements question-denied session permission rules when creating child
sessions via background task delegation. This prevents subagents from
asking questions by passing explicit permission configuration during
session creation.

🤖 GENERATED WITH ASSISTANCE OF OhMyOpenCode

src/features/background-agent/spawner.ts

@@ -61,6 +61,7 @@ export async function startTask(
   const createResult = await client.session.create({
     body: {
       parentID: input.parentSessionID,
+      ...(input.sessionPermission ? { permission: input.sessionPermission } : {}),
     } as Record<string, unknown>,
     query: {
       directory: parentDirectory,