* fix(llms): map default Claude Sonnet 4.6 to its 1M context window
Native AnthropicCompletion fell back to 200k for claude-sonnet-4-6, so the default instance understated the documented limit.
* fix(llms): align Anthropic context windows with active Claude models
Retired Claude 3/2/Instant IDs no longer have dedicated entries; the map now covers the current Claude API lineup and their documented 1M vs 200k windows.
* fix(llms): map Claude Mythos 5 to its documented 1M context window
Native AnthropicCompletion fell back to 200k for claude-mythos-5 even though Anthropic lists a 1M-token window.