Include generated docs in local circuit prompt

[NightVibes33]

Summary

• fetch the generated tscircuit docs from https://docs.tscircuit.com/ai.txt in createLocalCircuitPrompt
• keep the existing component props docs and handwritten API overview as fallback context
• cache the generated-docs fetch and continue prompt creation if the docs endpoint is unavailable
• add focused prompt-template coverage for docs inclusion, fallback behavior, and cache reuse
• gate OpenAI-dependent tests when no OPENAI_API_KEY is available so default test runs stay focused on repo logic

Verification

• GitHub Actions type-check: passing
• GitHub Actions test: passing
• git diff --check

/claim #45