Enhance alias filter functionality and improve data handling in Svelte components

- Updated the alias filter logic to prevent selected aliases from disappearing during partial or empty responses.
- Refactored the alias filter change handling to a dedicated function for better readability and maintainability.
- Removed redundant alias filter validation in the users page to streamline the alias selection process.

web/src/routes/+page.svelte

@@ -138,10 +138,15 @@
 			summary = s.data;
 			fleet = f.data ?? null;
 			uniqueIps = u.data ?? null;
-			availableAliases = collectAliases(
+			const nextAliases = collectAliases(
 				(fleet?.servers ?? []).map((x) => x.alias),
 				(summary?.servers ?? []).map((x) => x.alias)
 			);
+			// Не сужаем список до текущего фильтра: иначе выбранный alias
+			// может исчезать из селекта при частичных/пустых ответах.
+			availableAliases = Array.from(new Set([...availableAliases, ...nextAliases])).sort((a, b) =>
+				a.localeCompare(b)
+			);
 			lastSuccessAtMs = Date.now();
 
 			// Как бейдж «OK» в таблице: только health + system/info (без x.ok — в JSON поле ok опционально).
@@ -230,6 +235,11 @@
 	await load();
 	}
 
+async function handleAliasFilterChange(nextAlias: string) {
+	aliasFilter = nextAlias;
+	await applyAliasIfChanged(nextAlias);
+}
+
 	let queryKey = $derived(page.url.searchParams.toString());
 	$effect(() => {
 		queryKey;
@@ -526,10 +536,7 @@
 <AliasFilterSelect
 	availableAliases={availableAliases}
 	bind:value={aliasFilter}
-	onValueChange={(next) => {
-		aliasFilter = next;
-		void applyAliasIfChanged(next);
-	}}
+	onValueChange={(next) => void handleAliasFilterChange(next)}
 />
 	<FleetRefreshInput bind:value={refreshInput} onValueChange={() => void applyControls()} />
 </div>

web/src/routes/users/+page.svelte

@@ -172,7 +172,6 @@
 					.filter((a): a is string => typeof a === 'string' && a.length > 0)
 					.sort((a, b) => a.localeCompare(b));
 				availableAliases = aliases;
-				if (aliasFilter !== 'all' && !aliases.includes(aliasFilter)) aliasFilter = 'all';
 			} catch {
 				availableAliases = [];
 			}