Add comprehensive technical and architectural documentation

[Copilot]

• Create comprehensive technical and architectural documentation
  • Write main architecture overview document (ARCHITECTURE.md)
  • Document the three-layer cache system (Becca, Froca, Shaca)
  • Document entity system and data model
  • Document widget-based UI architecture
  • Document API architecture (Internal API, ETAPI, WebSocket)
  • Document monorepo structure
  • Document build system and tooling
  • Document database architecture (DATABASE.md)
  • Document synchronization system (SYNCHRONIZATION.md)
  • Document scripting system (SCRIPTING.md)
  • Document security architecture (SECURITY_ARCHITECTURE.md)
  • Create comprehensive index/table of contents (TECHNICAL_DOCUMENTATION.md)
  • Update docs/README.md with links to new documentation
  • Create quick reference guide (QUICK_REFERENCE.md)
  • Convert all ASCII diagrams to Mermaid.js format

Original prompt

Write a full technical and architectural documentation of the application in Markdown and place it in the docs dir.

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[eliandoran]

@copilot Can you modify the diagrams to use Mermaid.js instead?

[Copilot]

@copilot Can you modify the diagrams to use Mermaid.js instead?

Done! All ASCII diagrams have been converted to Mermaid.js format in commit 0494032.

The following diagrams were updated:

• ARCHITECTURE.md: High-level architecture, entity system, and UI layout
• SYNCHRONIZATION.md: Sync architecture with clients and server
• DATABASE.md: Data relationships between tables

All diagrams now use Mermaid.js with proper graph layouts, subgraphs for grouping, styled nodes with colors, and appropriate arrow types for relationships.

[github-actions]

📚 Documentation preview is ready!

🔗 Preview URL: https://pr-7600.trilium-docs.pages.dev
📖 Production URL: https://docs.triliumnotes.org

✅ All checks passed

This preview will be updated automatically with new commits.