feat(ui): F8-10 — tables planets / ship-groups / fleets, ship-classes delete guard (#53)

Lights up three previously-stubbed table active views and tightens the
existing one:

  - table-planets: 4 kind checkboxes (own / foreign / uninhabited /
    unknown) + race dropdown that filters the foreign slice; row click
    selects + centres the planet on the map.
  - table-ship-groups: local + foreign groups in one grid, owner
    checkboxes, planet dropdown (destination OR origin), class
    dropdown; on-planet click focuses the destination planet, in-space
    click focuses the ship group itself (camera follows interpolated
    position).
  - table-fleets: own fleets only with the shared planet dropdown;
    on-planet click focuses the planet, in-space click centres the
    camera on the interpolated fleet position without altering the
    selection (no fleet variant in Selected).
  - table-ship-classes: per-row Delete is disabled with a count tooltip
    while at least one local ship group references the class. The
    engine refuses the removal anyway; the UI pre-empts the surface.

Wires the click → map flow through a transient `SelectionStore.focus`
/ `focusPoint` channel that `map.svelte` consumes once on mount —
in-memory only, so an F5 does not re-centre.

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

ui/frontend/src/lib/active-view/table-ship-classes.svelte

@@ -73,6 +73,21 @@ data fetching is performed here — the layout is responsible.
 	);
 	const reportLoaded = $derived(rendered?.report !== null && rendered?.report !== undefined);
 
+	// inUseCounts is a derived index from class name → number of player
+	// ship groups currently referencing it. The engine refuses
+	// `removeShipClass` while any such group exists, so the table
+	// pre-emptively disables the per-row Delete affordance instead of
+	// surfacing a server-side rejection. The map is rebuilt whenever
+	// the rendered report changes; an empty report yields an empty map
+	// and every Delete stays enabled.
+	const inUseCounts = $derived.by(() => {
+		const map = new Map<string, number>();
+		for (const group of rendered?.report?.localShipGroups ?? []) {
+			map.set(group.class, (map.get(group.class) ?? 0) + 1);
+		}
+		return map;
+	});
+
 	const filtered = $derived.by(() => {
 		const needle = filter.trim().toLowerCase();
 		if (needle === "") return localShipClass;
@@ -123,6 +138,13 @@ data fetching is performed here — the layout is responsible.
 			name,
 		});
 	}
+
+	function deleteTooltip(count: number): string {
+		if (count === 0) return "";
+		return i18n.t("game.table.ship_classes.action.delete.in_use", {
+			count: String(count),
+		});
+	}
 </script>
 
 <section
@@ -189,6 +211,7 @@ data fetching is performed here — the layout is responsible.
 			</thead>
 			<tbody>
 				{#each sorted as cls (cls.name)}
+					{@const inUse = inUseCounts.get(cls.name) ?? 0}
 					<tr
 						data-testid="ship-classes-row"
 						data-name={cls.name}
@@ -215,6 +238,9 @@ data fetching is performed here — the layout is responsible.
 								type="button"
 								class="delete"
 								data-testid="ship-classes-delete"
+								data-in-use={inUse}
+								disabled={inUse > 0 || draft === undefined}
+								title={deleteTooltip(inUse)}
 								onclick={() => void deleteShipClass(cls.name)}
 							>
 								{i18n.t("game.table.ship_classes.action.delete")}