Rework templates into a component gallery

[GeneralJerel]

Problem

The current template system doesn't make sense from a UX perspective or for showcasing what Open Generative UI can do. Templates are a drawer of raw HTML strings — they don't communicate the value of agent-generated UI.

Proposal

Replace templates with a gallery of curated, saved conversation outputs. Each gallery item is a snapshot: 1 user message → 1 generated component. This lets visitors immediately see what the agent produces and interact with real outputs.

Gallery items should showcase two axes:

1. Explainers & Visualizations
Educational/explanatory generated components — things like:

• "How a Plane Flies" — interactive pitch/roll/yaw 3D explainer
• Binary search step-through
• Solar system model
• Neural network forward pass animation

These demonstrate the agent's ability to generate rich, interactive educational content from a simple prompt.

2. Custom UI & Styled Components
Generated components that match a specific design language or brand style:

• Clippy / paperclip-style assistant UI
• Spotify-inspired music dashboard
• Invoice card in a specific design system
• Themed dashboards

These demonstrate that generated UI isn't generic — the agent can produce components that feel intentionally designed.

Each gallery item includes:

• The original user prompt (1 message)
• The generated component output (rendered, interactive)
• Ability to download the generated component

Download capability

Users should be able to download generated components from the gallery. This connects to the broader artifact export story.

Related issues

• Save / Download Rendered Asset #14 — "Save / Download Rendered Asset" — downloading rendered visuals as PNG/SVG
• Add copy-as-code and download options for generated artifacts #42 — "Add copy-as-code and download options for generated artifacts" — copy-as-code and download as standalone HTML

Replaces

This supersedes the template drawer approach. The existing gallery plan (.chalk/plans/demo-gallery.md) should be updated to reflect this direction.