fix(core): honor maxImages in Anthropic CUA screenshot compression

[BABTUNA]

why

ClientOptions.maxImages existed, but Anthropic CUA still always used the default screenshot compression behavior (keepMostRecentCount = 2).

That means users could tune screenshot retention for Microsoft CUA, but Anthropic ignored the same option.

what to change

• Wire clientOptions.maxImages into AnthropicCUAClient
• Use that value when calling compressConversationImages(...)
• Keep existing default behavior when maxImages is not provided

validation

• Add/maintain unit tests covering:
  • default behavior (keep 2)
  • override behavior (e.g. keep 1)
  • maxImages=0 behavior