feat: render_map_tool support for Mapbox Standard Satellite base style

[mattpodwysocki]

Summary

Feature request (via Slack): support Mapbox Standard Satellite as a base map option for render_map_tool.

• New baseStyle: "standard" | "standard-satellite" input field, defaulting to "standard" — existing behavior is unchanged unless a caller opts in.
• "standard-satellite" loads Mapbox Standard Satellite — the same Standard style family (dynamic labels, bottom/middle/top slots for custom layers) rendered over global satellite imagery instead of a vector basemap. Confirmed against the Mapbox docs that it supports most, but not all, of baseMapConfig's properties (no theme, no flat-color overrides like colorWater/colorBuildings — there's no vector land/water surface under the imagery to recolor). Documented in docs/render-map-tool.md.
• Threaded through the same way baseMapConfig already is: MapAppPayload/MapAppPayloadSchema, RenderMapInputSchema, and assemblePayload() (including as a renderable field on its own, matching baseMapConfig's existing "restyle with no new data" behavior).
• mapAppHtml.ts picks the style URL from an explicit allowlist rather than interpolating the value directly, so an unrecognized baseStyle can never reach the style URL.
• Deliberately kept to an enum of the two Mapbox Standard-family styles rather than an open string, to stay aligned with this project's existing move away from Classic styles (feat: switch render_map_tool's base style from streets-v12 to Standard #248).

Test plan

• npx vitest run — all 944 tests pass, including new coverage in RenderMapTool.test.ts, mapAppPayload.test.ts, and mapAppHtml.script.test.ts (including a test that an unrecognized baseStyle value falls back to standard rather than being interpolated)
• npm run build succeeds, lint clean
• Live-verified in a real browser against the real Mapbox API: real satellite imagery loads via standard-satellite, with Standard's dynamic POI/road/place labels rendering on top and a custom route layer drawn correctly above it — screenshot included in docs/render-map-tool.md

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