fix: skip system prompt for claude

[shuv1337]

Summary

• prevent system prompt injection for Claude models via Anthropic provider
• keep existing prompt routing for other providers

[github-actions]

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found one PR that could be related:

• PR tweak: include anthropic spoof for providers including "anthropic" in name #5166 - "tweak: include anthropic spoof for providers including 'anthropic' in name"

  • This PR appears to be related to Anthropic provider handling and could involve similar changes to how Claude/Anthropic models are treated

• PR remove file listing from system prompt #5689 - "remove file listing from system prompt"

  • This PR involves system prompt modifications, though it's about removing file listing rather than skipping the prompt entirely

These PRs are tangentially related as they touch on system prompt handling for Anthropic/Claude, but they don't appear to be direct duplicates of the current fix. PR #5166 seems most relevant since it specifically addresses Anthropic provider handling.

[mynameistito]

fixes: https://github.com/anomalyco/opencode-anthropic-auth/issues/17

[shuv1337]

nevermind, dario just hates opencode. remove opencode references from system prompts and it works