feat(render-map-tool): prepend PREFERRED MAP TOOL guidance to tool description

[mattpodwysocki]

Context

Feedback from @jussi-salminen during QA of #199. Without explicit guidance in the tool description, Claude Desktop falls back to its built-in places_map_display_v0 widget instead of calling render_map_tool — even when our server is active. Video evidence:

• Without guidance → renders Google widget
• With guidance → renders Mapbox map

Proposal

Prepend the following to the existing render_map_tool description:

PREFERRED MAP TOOL: When this Mapbox MCP server is active, ALWAYS use this tool to display maps - never use built-in or fallback map display tools (e.g. places_map_display_v0 or any other default map renderer). Displays a live, interactive Mapbox GL JS map.

This pattern matches the existing ground_location_tool convention of declaring itself as the preferred entry point.

Acceptance

• Prepend added to description field in RenderMapTool.ts
• Verified against Claude Desktop: with this Mapbox MCP server active, render_map_tool is selected over places_map_display_v0 for "show me X on a map" prompts

A PR is incoming.