feat: editor improvements and architectural grid prototype

Multiple feature additions and improvements across the application:

- NextGen Editor: drag handles, smart paste, block actions
- Structured views: Kanban and table layouts for notes
- Architectural Grid: new brainstorming/agent interface prototype
- Flashcards: SM-2 revision algorithm with AI generation
- MCP server: robustness improvements
- Graph/PDF chat: fix click propagation and copy behavior
- Various UI/UX enhancements and bug fixes

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

architectural-grid1/README.md

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+<div align="center">
+<img width="1200" height="475" alt="GHBanner" src="https://ai.google.dev/static/site-assets/images/share-ais-513315318.png" />
+</div>
+
+# Run and deploy your AI Studio app
+
+This contains everything you need to run your app locally.
+
+View your app in AI Studio: https://ai.studio/apps/b7b577c6-4d9f-44ac-8fe1-85bc3c6d6e66
+
+## Run Locally
+
+**Prerequisites:**  Node.js
+
+
+1. Install dependencies:
+   `npm install`
+2. Set the `GEMINI_API_KEY` in [.env.local](.env.local) to your Gemini API key
+3. Run the app:
+   `npm run dev`