v1.4.457

Changes

PR #2155 by ksylvan: Claude Sonnet 5 Anthropic support

• Add Claude Sonnet 5 to supported Anthropic models
• Enable one-million-token context beta for Claude 5 models
• Omit sampling parameters for Claude Sonnet 5 requests
• Centralize Anthropic sampling restrictions behind prefix matching
• Remove older Claude 4 aliases from model listings

PR #2156 by ksylvan: Make it possible to back-fill missing ChangeLog entries

• Add support for changelog generation for closed pull requests via a new --closed-ok flag, bypassing open-state validation.
• Skip mergeability checks when processing closed pull requests to allow smooth back-filling of missing entries.
• Store the closed pull request allowance setting in the generator configuration for consistent behavior.
• Improve error messaging to guide users toward using --closed-ok when validation errors occur on closed PRs.
• Introduce the --closed-ok flag as the primary mechanism for enabling back-fill workflows on previously closed pull requests.