fix: remove stale [Context Restoration] and [Working Directory] assertions from compaction test

The [Working Directory] section was removed from buildPostCompactContext
since it's redundant with the system prompt's Primary working directory
field. This means contextParts can be empty in test scenarios with no
file reads/plan/skills/background tasks, so [Context Restoration] is
never appended. Remove both assertions.

Author: lewis617

packages/agent-sdk/tests/agent/agent.compaction.test.ts

@@ -535,8 +535,6 @@ describe("Agent Message Compaction Tests", () => {
     expect(compactBlock.content).toContain(
       "Compacted content: This contains summary information of previous multi-round conversations.",
     );
-    expect(compactBlock.content).toContain("[Context Restoration]");
-    expect(compactBlock.content).toContain("[Working Directory]");
 
     // Reset messagesPassedToCallAgent to capture parameters for the second call
     messagesPassedToCallAgent = [];