fix(ui-map): repaint fog as layered overpaint; rename to visibleHyperspace

The Phase 29 fog overlay rendered as a handful of random arc
segments instead of a clean union of holes around LOCAL planets
— Pixi v8's `Graphics.cut()` does not reliably subtract multiple
overlapping circles from a base path.

Replaced the cut-based approach with a layered overpaint: a
fog-tinted rectangle fills the world, then opaque background-
coloured circles are painted on top for every visibility circle.
The natural rendering order unions overlapping circles for free —
no geometry, no `cut()` quirks, one extra fill per circle.

Renamed the toggle from `visibilityFog` to `visibleHyperspace`
across the store, i18n strings, popover, tests, and docs. The
overlay still implements the visual "fog" effect at the renderer
level (FOG_COLOR, setVisibilityFog, getMapFog); the toggle is
named after the player-facing concept it controls — the portion
of the map that is visible (intelligence/scan coverage) — rather
than the obscured part.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/frontend/tests/e2e/map-toggles.spec.ts

@@ -306,7 +306,7 @@ test("visibility fog toggles between the LOCAL-planet circle list and an empty o
 	expect(initialFog[1].radius).toBe(300);
 
 	await page.getByTestId("map-toggles-trigger").click();
-	await page.getByTestId("map-toggles-visibility-fog").click();
+	await page.getByTestId("map-toggles-visible-hyperspace").click();
 
 	// The effect re-run is async; wait for the fog payload to clear
 	// instead of reading it on the next tick.
@@ -315,7 +315,7 @@ test("visibility fog toggles between the LOCAL-planet circle list and an empty o
 	);
 
 	// Toggling back on rebuilds the fog circles for the same planets.
-	await page.getByTestId("map-toggles-visibility-fog").click();
+	await page.getByTestId("map-toggles-visible-hyperspace").click();
 	await page.waitForFunction(
 		() => window.__galaxyDebug!.getMapFog!().circles.length === 2,
 	);