feat: add open_notebook plugin

[twilso24]

Connect Agent Zero to Open Notebook for notebook browsing, source management, name-based lookup, notes, podcasts, and a right-canvas knowledge panel.

• GitHub: https://github.com/twilso24/open_notebook_agent_zero
• Tags: integration, tools, llm, knowledge, web

What’s included

• Notebook browsing with ID visibility in the browse view
• Name-based notebook resolution across tools
• Parameter aliases for more natural tool usage
• Fully working CRUD flows for sources and notes
• Podcast generation support
• UI cleanup and scroll fixes in the right-canvas panel
• Removed broken global search UI
• Removed unused Cloudflare tunnel support and related references
• Removed obsolete search/ask beta feature references

Checklist

• index.yaml in plugins/open_notebook/
• Folder name matches ^[a-z0-9_]+$
• Remote plugin.yaml has name: open_notebook matching folder name
• Remote LICENSE exists at repo root (MIT)
• Remote README.md present
• Tags from TAGS.md (max 5)
• No duplicate in existing index

[a0-bot]

Plugin submission validation failed

ERROR: PR must modify exactly one plugin folder under plugins/

[a0-bot]

Plugin submission validation failed

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