Fix CI lint errors and test failures

- test_memory_sync.py: remove unused imports (asyncio, MagicMock,
  AgentMemory, AgentMemoryAdapter, SyncResult), fix import sorting
- test_ws_memory_relay.py: remove unused pytest import and unused
  output_index variable, fix import sorting
- test_wrap_copilot.py: provide dummy API keys in test env — the
  BYOK validation added in 7a7b8b6 requires ANTHROPIC_API_KEY or
  OPENAI_API_KEY to be set
- test_package_init_lazy.py: stop hardcoding version string that
  breaks on every bump; assert it's a non-empty string instead

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>