Core map APIs: basemap switching, zoom, and pointer-event streams

[CarsonDavis]

Description

First half of the split of #115 (MapControl plugin, by @BhattaraiSijan) — the core/engine capabilities, with the plugin itself following in a stacked PR. Split so the reusable core API surface gets reviewed on its own terms, separate from the ~1,200 lines of plugin UI that consume it. Content is @BhattaraiSijan's work rebased onto current development (44 commits ahead of #115's base, no conflicts); commits are attributed to the original author.

Part of #98.

New map:* bus handlers + documented mmgisAPI methods

Added in Map_.js and exposed on mmgisAPI, usable by any plugin:

• setBasemap / getBasemap / getBasemapStyles — switch between named basemap styles. Styles come from msv.basemap.styles[] in the mission config, falling back to per-engine provider defaults (Leaflet → raster XYZ tile templates, deck.gl → vector style JSON).
• zoomIn / zoomOut — clamped to the engine's min/max zoom.
• latLngToContainerPoint — project {lat, lng} to container pixels, for positioning DOM overlays.
• map:click / map:mousemove pointer streams re-emitted onto the event bus.

Engine adapters

• LeafletAdapter gains runtime basemap rendering (it previously had none): mapbox:// styles resolve to Mapbox raster tile URLs (requires an access token), raw {z}/{x}/{y} templates render directly, and GL style URLs are skipped with a warning rather than silently rendering the wrong thing.
• Behavior fix worth calling out: LeafletAdapter.createLayer now replaces an existing layer on a duplicate id instead of orphaning the old layer on the map with no registry entry left to remove it by.
• DeckGLAdapter gains setStyle (swaps the vector style in place) and normalized {lat, lng} pointer-event emission.
• view.ts gains BasemapStyleEntry and extends basemap config/docs to cover both engines.

Configure page

• Basemap configuration now applies to any engine (was deck.gl-only); field descriptions updated to match.
• New Earth missions get a default continental-US view; switching engines in the new-mission modal clears the basemap fields so values entered for one engine don't silently ship with another.

Differences from #115 (this portion)

• Dropped two stale auto-version-bump package.json hunks (that workflow was removed in Stop auto-bumping the project version on every pull request #225) and three formatting-only reflow hunks (mmgisAPI.js ×2, DeckGLAdapter.ts ×1) with zero semantic change.
• One comment in Map_.js reworded to not name the MapControl plugin, which only lands in the stacked PR.

Testing

• Full unit suite passes on this branch (889 tests, vitest run).
• npm run build succeeds on this branch standing alone.
• Manual verification steps for the whole feature are in Feat/mapcontrol plugin #115; the plugin PR stacked on this one exercises every API added here.