Include generated docs in local circuit prompt

[SimplyRayYZL]

Summary

• Loads the generated tscircuit docs feed from https://docs.tscircuit.com/ai.txt alongside the props docs.
• Inserts the generated docs into the local circuit system prompt.
• Keeps prompt creation resilient if the optional generated docs endpoint is unavailable.
• Adds mocked-fetch coverage for inclusion and fallback behavior.
• Keeps OpenAI-dependent prompt tests deterministic by honoring injected clients.

Validation

• bun test --timeout 50000
• bun x tsc --noEmit
• bun run build
• GitHub Actions: Bun Test and Type Check passing on 68690bb

/claim #45
Closes #45