docs: add module diagrams and remove markers

[AchintyaAshok]

Summary

• convert sync script to heading-based updates and drop CLAUDE markers
• document architecture of each module with mermaid diagrams
• keep AGENTS files synced from CLAUDE.md content

Testing

• node scripts/sync-claude-agents.js
• npm test (heavy logging, completes)
• npm run lint

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https://chatgpt.com/codex/tasks/task_b_68bb015c3bec8330a93d2ed4e8fe703e

[github-actions]

🤖 Changeset Status

⚠️ No changeset found - This PR will default to patch version when merged.

Is this the right version bump?

• 🐛 Bug fixes, small improvements → Automatic patch is perfect! ✅
• ✨ New features, API additions → Consider adding a minor changeset
• 💥 Breaking changes → Please add a major changeset

How to add a changeset:

1. Run npx changeset in your terminal
2. Select the appropriate version bump (patch/minor/major)
3. Write a short description of your changes
4. Commit the generated .changeset/*.md file

Skip release entirely:

Add [skip-ci] to your PR title if this shouldn't trigger any release.

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