feat: add app edit page with pre-populated form

Add /apps/[id]/edit route that loads existing app data into the form,
allowing users to update app properties. Adds edit pencil button to
AppCard (visible on hover) and i18n keys for both EN and RU.

src/lib/components/app/AppForm.svelte

@@ -14,12 +14,13 @@
 	interface Props {
 		form: SuperValidated<AppSchema>;
 		action?: string;
+		mode?: 'create' | 'edit';
 	}
 
-	let { form: formData, action = '?/create' }: Props = $props();
+	let { form: formData, action = '?/create', mode = 'create' }: Props = $props();
 
 	const { form, errors, enhance, submitting } = superForm(formData, {
-		resetForm: true
+		resetForm: mode === 'create'
 	});
 
 	let showAdvanced = $state(false);
@@ -383,7 +384,7 @@
 			{#if $submitting}
 				{$t('app.saving')}
 			{:else}
-				{$t('app.save')}
+				{mode === 'edit' ? $t('app.update') : $t('app.save')}
 			{/if}
 		</button>
 	</div>