Intent of copilotAgent.ts ×5

All 3 exact tests in this concept. Every test is marked by where it enters the hierarchy.

mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/ 3 tests
- platform/ 3 tests
  - agentHost/ 3 tests
    
    test/ 3 tests
    
    node/ 3 tests
    
    copilotAgent.test|title=CopilotAgent peer chat create / 2 tests
    
    fork / 2 tests
    
    model+agent / 2 tests
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/platform/agentHost/test/node/copilotAgent.test|title=CopilotAgent peer chat create / fork / model+agent / restore round-trip materializeChat falls back to the legacy copilot.chats catalog when providerData is undefined|occurrence=1 Inherited copilotAgent.ts ×8
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/platform/agentHost/test/node/copilotAgent.test|title=CopilotAgent peer chat create / fork / model+agent / restore round-trip round-trips peer chats through providerData + materializeChat and resumes per-chat history after a restart|occurrence=1 Inherited copilotAgent.ts ×4
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/platform/agentHost/test/node/copilotAgent.test|title=CopilotAgent peer chat routing and lifecycle disposeChat deletes the SDK chat (via legacy fallback) and drops the live backing without rewriting copilot.chats|occurrence=1 Inherited copilotAgent.ts ×1