feat: sonnet 4.5 updates, 3.5 deprecation

[RomneyDa]

Description

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• [] I've read the contributing guide
• [] The relevant docs, if any, have been updated or created
• [] The relevant tests, if any, have been updated or created

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Summary by cubic

Upgrade Anthropic models to Claude Sonnet 4/4.5 and phase out 3.5 references across configs, UI, schemas, and tests. Adds 4.5 Sonnet and Haiku support and simplifies tool capability detection.

• New Features

  • Added Claude Sonnet 4.5 and Haiku 4.5 (Anthropic and CometAPI), plus Opus 4.1 with full metadata, regex, and GUI packages.
  • Updated defaults and samples: IntelliJ and workspace templates, VSCode schema enums, common slugs, and docs links.
  • Refreshed tests and e2e configs to use new Anthropic model IDs (Anthropic, OpenRouter, adapters).
  • Simplified tool support detection to prefix-based checks for claude/gpt-4/o3/gemini/gemma.

• Migration

  • Replace claude-3-5-sonnet(-latest) with claude-sonnet-4-5 or claude-sonnet-4(-latest).
  • Replace claude-3-5-haiku(-latest) with claude-haiku-4-5.
  • Update YAML and OpenRouter slugs (e.g., anthropic/claude-3.5-sonnet → anthropic/claude-sonnet-4-5).

[chezsmithy]

@RomneyDa I believe maxtokens for both sonnet 4.5 and haiku 4.5 is now 64,000.

[bdougie]

@RomneyDa can you also update Model recommendation table in this https://docs.continue.dev/customization/models