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.test.ts

@@ -3,7 +3,7 @@ import { describe, test, expect } from "bun:test"
 import { createTask, startTask } from "./spawner"
 
 describe("background-agent spawner.startTask", () => {
-  test("does not override parent session permission rules when creating child session", async () => {
+  test("applies explicit child session permission rules when creating child session", async () => {
     //#given
     const createCalls: any[] = []
     const parentPermission = [
@@ -41,6 +41,9 @@ describe("background-agent spawner.startTask", () => {
         parentModel: task.parentModel,
         parentAgent: task.parentAgent,
         model: task.model,
+        sessionPermission: [
+          { permission: "question", action: "deny", pattern: "*" },
+        ],
       },
     }
 
@@ -57,6 +60,8 @@ describe("background-agent spawner.startTask", () => {
 
     //#then
     expect(createCalls).toHaveLength(1)
-    expect(createCalls[0]?.body?.permission).toBeUndefined()
+    expect(createCalls[0]?.body?.permission).toEqual([
+      { permission: "question", action: "deny", pattern: "*" },
+    ])
   })
 })