feat(experts): add Karpathy knowledge base expert

[Pandakingxbc]

Summary

• add a bundled Karpathy-style LLM Wiki expert
• initialize bounded MEMORY.md, immutable raw sources, and AI-maintained wiki index/overview/log
• add ingest/query/lint workflows and expert-template regression coverage
• preserve configured workspace path spelling so macOS firmlink resolution does not break artifact de-duplication

Verification

• pre-commit hook passed without bypass
• Ruff check and formatting passed
• mypy passed for 438 source files
• pytest: 2438 passed, 46 skipped
• dashboard TypeScript/Vite/PWA production build passed
• skill/frontmatter and manifest validation passed