Dashboard JSON import: provide more descriptive error messages, improve docs and MCP, add examples/templates

[simon-liebehenschel]

Now

A vague error: Field required

What field? How am I supposed to guess that?

A non‑descriptive error: can't access property "display", m is undefined

I have no idea what that means, and searching yields no results.

Expected behavior

• Provide more detailed messages.
• Better document dashboard creation and include templates and examples for common services (e.g., dashboards for Redis, MongoDB, etc.).
• Extend the Logfire MCP to assist AI agents with dashboard creation. Currently, the Logfire documentation and Logfire MCP do not provide enough information for an AI agent to generate a valid output.