chore: add docs/assets directory for demo GIF

docs: add Reddit and Hacker News launch post drafts

docs: add language tutors example party

docs: add fullstack team example party

docs: add GitHub issue and PR templates

docs: add contributing guide

docs: restructure Japanese README to match landing page format

docs: restructure Simplified Chinese README to match landing page format

docs: restructure Traditional Chinese README to match landing page format

docs: restructure README as landing page with badges and value proposition

ci: add GitHub Actions workflow for pytest

docs: add community growth implementation plan

docs: add community growth design spec

fix: strengthen orchestration rules for reliable always-trigger sub-agents

docs: add Traditional Chinese, Simplified Chinese, and Japanese README translations