Updates the ClickHouse chat agent example page to match the upgraded
example (triggerdotdev/examples#124), which is now a fullstack
generative-UI chat app rather than an agent-only project.

## What changed

- **Overview / tech stack / features** rewritten: Next.js chat app
(`useChat` + `useTriggerChatTransport`, no API route), a
`renderVisualization` tool taking json-render specs rendered with
`@json-render/shadcn` + shadcn charts (Recharts) + mapcn point maps, and
a shared catalog that generates both the system-prompt component
reference and tool-call validation.
- **The agent section** now shows the versioned [AI
Prompt](https://trigger.dev/docs/ai/prompts) pattern (`prompts.define()`
+ `chat.prompt.set()` + `chat.toStreamTextOptions({ registry })`), with
a warning that `experimental_telemetry` comes from the stored prompt —
the docs previously showed a static `system:` string, which silently
ships no LLM observability.
- **New sections** for the shared catalog, the `renderVisualization`
tool, the Next.js chat UI and registry.
- **Relevant code links** updated to the new `src/` layout.
- **Learn more** cards now include Frontend and AI Prompts.

Note: merge after triggerdotdev/examples#124 lands, so the GitHub file
links resolve.

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