Summary

• Add @tnezdev/agentic-runtime-local as the first runtime package in the monorepo.
• Export a valid local runtime manifest with thin init, placeholder run, and cheap status handlers.
• Document that future Pi integration means https://pi.dev/ and does not change the public local target.

Closes #108

Test plan

• bun test
• bun run typecheck
• bun run build
• npm pack --dry-run from packages/agentic-runtime-local
• git diff --check