fix(sdk): import JSONL persistence as a plugin namespace in resume tests

#5938 turned @deepseek-ai/dsh-session-persistence-jsonl into a function
plugin without a default export, while the SDK resume spec from #5988
still default-imported it. Typecheck failed with TS1192 and the spec's
six cases mounted an undefined plugin, which kept the coverage, snapshot
and Windows build checks red for every pull request.

packages/sdk/server/tests/resume.spec.ts

@@ -6,7 +6,7 @@ import { Context } from '@deepseek-ai/cordis'
 import AgentLoop from '@deepseek-ai/dsh-agent-loop'
 import { mountAgentLoopTestDependencies } from '@deepseek-ai/dsh-agent-loop-testkit'
 import { SessionId, SessionSeq } from '@deepseek-ai/dsh-session'
-import JsonlSessionPersistence from '@deepseek-ai/dsh-session-persistence-jsonl'
+import * as JsonlSessionPersistence from '@deepseek-ai/dsh-session-persistence-jsonl'
 import type { JsonRpcTransportPeer, SessionEventNotification } from '@deepseek-ai/dsh-sdk-protocol'
 import { MockAdapter, textResponse } from '../../../core/agent-loop/tests/mock-adapter.ts'
 import { HarnessSdkJsonRpcServer } from '../src/index.ts'