[codex] add local-first source auto-refresh

[0dust]

Summary

• Add local registered website sources with okfy add, sources, check, update, remove, OKFY_HOME, source.json, and state.json.
• Add age-based freshness, safe temp-bundle refresh/replacement, bundle hashing, duration parsing, lock/throttle handling, and failure preservation.
• Add source-name MCP serving with gated --auto-refresh, stale-while-refresh/blocking modes, reloadable search, and bundle_summary freshness metadata.
• Update agent-first README/MCP docs and add the PRD plus unit/integration coverage.

Notes

• okfy update <name> is now the explicit refresh-now command; there is no update --force flag.
• serve <source> --mcp reports source freshness metadata without network refresh; --auto-refresh enables refresh behavior.
• The regenerated dist/chunk-* file is the expected tsup shared chunk replacement.

Validation

• pnpm lint
• pnpm typecheck
• pnpm test (10 files, 63 tests)
• pnpm build
• pnpm demo
• npm pack --dry-run
• Manual local HTTP fixture flow: add, sources, check, update, and serve stripe --mcp --auto-refresh with JSON-RPC-only stdout and fresh/valid bundle_summary.