feat(ui): error & state UX — error surface, view states, map selection, sheet gestures (F4)

- lib/error/: classify any caught error into a stable ErrorKind from the
  transport signal (HTTP status / Connect Code / fetch TypeError /
  navigator.onLine); map to translated error.* messages via reportError
  (sticky Retry toast for retryable kinds) or errorMessageKey (inline).
  Mail compose now surfaces the translated 403/error inline.
- lib/ui/view-state.svelte: shared loading/empty/error placeholder with
  the right live-region role + optional action; entity tables
  (races/sciences/ship-classes) migrated, rest adopt incrementally.
- map/selection-ring.ts: accent ring around the selected planet, fed into
  the map buildExtras alongside the reach circles.
- lib/ui/sheet-dismiss.ts: tap-outside + drag-handle swipe-down dismissal
  for the planet/ship-group bottom-sheets (hand-rolled pointer events).

Tests: error, view-state, selection-ring, sheet-dismiss (761 total).
Docs: ui/docs/error-state-ux.md (+ index); F4 marked done.

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

ui/frontend/src/lib/active-view/map.svelte

@@ -32,6 +32,7 @@ preference the store already manages.
 	import { buildCargoRouteLines } from "../../map/cargo-routes";
 	import { buildPendingSendLines } from "../../map/pending-send-routes";
 	import { computeReachCircles } from "../../map/reach-circles";
+	import { computeSelectionRing } from "../../map/selection-ring";
 	import { reachStore } from "$lib/calculator/reach.svelte";
 	import {
 		reportToWorld,
@@ -202,6 +203,8 @@ preference the store already manages.
 		// redraw as the design or the selected planet changes.
 		void reachStore.origin;
 		void reachStore.speedPerTurn;
+		// Redraw the selected-planet ring when the selection changes.
+		void selection?.selected;
 
 		// Phase 29 visibility derivation. Cargo routes and pending-
 		// Send overlay are extras (no Pixi remount on flip); the
@@ -231,9 +234,11 @@ preference the store already manages.
 			reachOrigin === null
 				? ""
 				: `${reachOrigin.x},${reachOrigin.y},${reachStore.speedPerTurn}`;
+		const selectedPlanetId =
+			selection?.selected?.kind === "planet" ? selection.selected.id : null;
 		const extrasFingerprint =
 			`cr=${toggles.cargoRoutes ? "1" : "0"}|hp=${hiddenPlanetFingerprint}|` +
-			`reach=${reachFingerprint}|` +
+			`reach=${reachFingerprint}|sel=${selectedPlanetId ?? ""}|` +
 			computeRoutesFingerprint(report.routes) +
 			"|" +
 			computePendingSendFingerprint(draftCommands, draftStatuses);
@@ -329,7 +334,15 @@ preference the store already manages.
 						mode,
 					)
 				: [];
-		return [...cargo, ...pending, ...reach];
+		const selectedPlanetId =
+			selection?.selected?.kind === "planet" ? selection.selected.id : null;
+		const selectionRing = computeSelectionRing(report.planets, selectedPlanetId);
+		return [
+			...cargo,
+			...pending,
+			...reach,
+			...(selectionRing === null ? [] : [selectionRing]),
+		];
 	}
 
 	function applyVisibilityState(