Include generated docs in local circuit prompt

[tracepatch-lab]

Summary

• load https://docs.tscircuit.com/ai.txt as optional generated-doc context for createLocalCircuitPrompt
• fetch generated docs in parallel with the existing component props docs
• cache generated docs during the process and keep prompt generation resilient if the endpoint fails
• omit the generated-docs section when the optional endpoint is unavailable, instead of leaving an empty prompt section
• add deterministic mocked-fetch tests for inclusion and fallback behavior

Fixes #45

Verification

bun test tests/create-local-circuit-prompt.test.ts
2 pass
0 fail
5 expect() calls

biome check lib/prompt-templates/create-local-circuit-prompt.ts tests/create-local-circuit-prompt.test.ts
Checked 2 files. No fixes applied.

node node_modules/typescript/bin/tsc --noEmit --pretty false

node node_modules/tsup/dist/cli-node.js lib/index.ts --format esm --dts
Build success

/claim #45

[tracepatch-lab]

/claim #45

[tracepatch-lab]

Ready for review. This PR links Fixes #45, includes /claim #45, and has local verification for the focused test, Biome, TypeScript, and build in the PR body.

Happy to adjust if you want the generated-docs section placed elsewhere in the prompt.