feat: add Global Brain & Neural-Bus architecture documentation

[Delqhi]

Summary

• Created docs/architecture/global-brain-neural-bus.md with complete documentation
• Updated VitePress sidebar config with new Architecture section
• Added .pcpm knowledge base
• Updated docs/index.md with ecosystem links

Documentation Added

• Global Brain (PCPM) overview, CLI commands, MCP tools, project brain structure
• Neural-Bus (JetStream) architecture, core exports, subject taxonomy
• Durable consumer pattern and lesson publishing examples
• Local verification instructions

Files Changed

• docs/architecture/global-brain-neural-bus.md (new)
• .vitepress/config.js (updated sidebar)
• docs/index.md (updated ecosystem links)
• .pcpm/ (new - 4 files)

Related

• Global Brain: https://github.com/Delqhi/global-brain
• Neural-Bus: https://github.com/OpenSIN-AI/OpenSIN-Neural-Bus

[Delqhi]

Already merged via commit 4bb708f (PR #93). Closing as completed.