feat(ui): F8-12 — map polish (zoom invariance, labels, selection, soft radius) (#55)

* Honest pixel-space sizing for `pointRadiusPx` / `strokeWidthPx`: the
  renderer divides by the current camera scale on every
  `viewport.zoomed` so thin lines / small markers stay the same on-screen
  size at any zoom.
* Known-size planets switch to `pointRadiusWorld`, softened against the
  reference scale by `PLANET_SIZE_ZOOM_ALPHA = 0.33`; unidentified
  planets pin to a 3-px disc.
* New planet label layer renders a two-line `name / #N` legend under
  each planet (`#N` only for unidentified or when the new `planetNames`
  toggle is off). Selection now paints an inverse-fill frame around the
  selected planet's label plus an outline on the disc; the old
  selection-ring primitive is retired.
* Bombing markers swap the separate CirclePrim for a planet-outline
  overlay (damaged / wiped colour); the report deep-link moves to a
  "view bombing report" link in the planet inspector.
* Docs + tests follow: `renderer.md` reflects the new sizing contract +
  label / outline layers, vitest covers the sizing math, label
  formatting, and the new toggle, and the map-toggles e2e adds a
  persistence case for `planetNames`.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ui/frontend/src/lib/game-state.svelte.ts

@@ -57,6 +57,14 @@ export interface MapToggles {
 	cargoRoutes: boolean;
 	battleMarkers: boolean;
 	bombingMarkers: boolean;
+	/**
+	 * planetNames toggles the on-map two-line label drawn under each
+	 * planet (F8-12 / issue #55, п.29). When ON, the first line shows
+	 * the planet name (when known) and the second line shows `#N`.
+	 * When OFF, the name line is suppressed for every planet — only
+	 * `#N` remains. Default ON.
+	 */
+	planetNames: boolean;
 	/**
 	 * visibleHyperspace toggles the foggy overlay that darkens the
 	 * world OUTSIDE the union of `VisibilityDistance` circles around
@@ -78,6 +86,7 @@ export const DEFAULT_MAP_TOGGLES: MapToggles = {
 	cargoRoutes: true,
 	battleMarkers: true,
 	bombingMarkers: true,
+	planetNames: true,
 	visibleHyperspace: true,
 };