Template gallery with curated prompt examples #49

Summary

Add a template gallery that showcases curated prompt examples users can browse and apply with one click. This improves discoverability of what the agent can do and gives users a starting point for common visualizations.

Motivation

Currently, templates are only created by saving agent-generated UIs. New users don't have any templates to start with and may not know what kinds of visualizations are possible. A gallery of pre-built prompts and templates would:

• Lower the barrier to entry for new users
• Showcase the agent's capabilities (diagrams, charts, dashboards, 3D, etc.)
• Provide reusable starting points that users can customize

Proposed Changes

• Prompt gallery UI: A browsable grid/carousel of example prompts with preview thumbnails
• Curated prompt collection: Pre-built prompts organized by category (e.g. diagrams, charts, dashboards, interactive widgets, 3D scenes)
• One-click apply: Clicking a gallery item sends the prompt to the agent
• Template improvements: Better template management (rename, categorize, preview thumbnails)

Open Questions

• Should gallery prompts be bundled in the repo or fetched from an external source?
• Should the gallery be a separate view or integrated into the chat sidebar?
• Should users be able to contribute their own prompts to the gallery?