fix: omit temperature for Claude models that reject it

[ehammond]

Problem

Running any abc command with the default claude-opus-4-8 model failed:

[abc] [ERROR] An unexpected error occurred: Error code: 400 - {'type': 'error',
'error': {'type': 'invalid_request_error', 'message': '`temperature` is deprecated for this model.'}}

Newer Claude models (Opus 4.7+, Sonnet 5, Fable 5) removed the temperature parameter and return a 400 for any value, including the default 0.0. The Anthropic provider hardcoded temperature=self.temperature into every request, so every call broke.

Fix

• Make temperature opt-in in the Anthropic provider: only include it in the request when the user explicitly sets one in their config. Omitted otherwise, which works on all current models while still supporting older models for anyone who configures it.
• Update the stale default model from claude-opus-4-5 to claude-opus-4-8.
• Bump all version strings to 2026.07.15.

Testing

• Unit tests updated: temperature defaults to None; added coverage that it's omitted by default and sent when configured.
• Verified end-to-end against the real API — abc_generate "print hello" now returns a command instead of the 400.

[Created with AI: Claude Code with Opus 4.8]

https://claude.ai/code/session_011AkFCoUHqunn97PjiJKK8R