fix(ci): resolve mock.module() cross-file leakage in test suite

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/features/background-agent/abort-with-timeout.test.ts

@@ -6,9 +6,11 @@ mock.module("../../shared", () => ({
   log: logMock,
 }))
 
-import { abortWithTimeout } from "./abort-with-timeout"
 import type { OpencodeClient } from "./opencode-client"
 
+const { abortWithTimeout } = await import("./abort-with-timeout")
+mock.restore()
+
 function createClient(abort: (...args: Array<unknown>) => Promise<unknown>): OpencodeClient {
   return {
     session: {