feat: locale-aware notification templates + UX improvements

- Add locale support to notification templates (matching command template
  pattern): TemplateSlot now has locale field with (config_id, slot_name,
  locale) uniqueness, nested API format {slot: {locale: template}}
- Migration merges separate EN/RU system configs into unified per-provider
  configs; seeds create one config per provider with multi-locale slots
- Locale-aware dispatch with EN fallback in NotificationDispatcher
- Frontend locale tabs (EN/RU) on template config editor
- Fix tracking config cards not showing default provider icons
- Global provider filter, search palette, and various UX polish

frontend/src/routes/tracking-configs/+page.svelte

@@ -14,17 +14,19 @@
 	import Hint from '$lib/components/Hint.svelte';
 	import IconButton from '$lib/components/IconButton.svelte';
 	import IconGridSelect from '$lib/components/IconGridSelect.svelte';
-	import { providerTypeItems, providerTypeFilterItems, sortByItems, sortOrderItems, albumModeItems, assetTypeItems, memorySourceItems } from '$lib/grid-items';
+	import { providerTypeItems, providerTypeFilterItems, sortByItems, sortOrderItems, albumModeItems, assetTypeItems, memorySourceItems, providerDefaultIcon } from '$lib/grid-items';
 	import { snackSuccess, snackError } from '$lib/stores/snackbar.svelte';
 	import { highlightFromUrl } from '$lib/highlight';
+	import { globalProviderFilter } from '$lib/stores/provider-filter.svelte';
 	import type { TrackingConfig } from '$lib/types';
 
 	let allConfigs = $derived(trackingConfigsCache.items);
 	let filterText = $state('');
 	let filterType = $state('');
+	let effectiveType = $derived(globalProviderFilter.providerType || filterType);
 	let configs = $derived(allConfigs.filter(c =>
 		(!filterText || c.name.toLowerCase().includes(filterText.toLowerCase())) &&
-		(!filterType || c.provider_type === filterType)
+		(!effectiveType || c.provider_type === effectiveType)
 	));
 	let loaded = $state(false);
 	let showForm = $state(false);
@@ -262,9 +264,11 @@
 <div class="flex items-center gap-2 mb-3">
 	<input type="text" bind:value={filterText} placeholder={t('common.filterByName')}
 		class="flex-1 px-3 py-1.5 border border-[var(--color-border)] rounded-md text-sm bg-[var(--color-background)]" />
+	{#if !globalProviderFilter.id}
 	<div class="w-48">
 		<IconGridSelect items={providerTypeFilterItems()} bind:value={filterType} columns={2} compact />
 	</div>
+	{/if}
 </div>
 {/if}
 
@@ -283,7 +287,7 @@
 				<div class="flex items-center justify-between">
 					<div>
 						<div class="flex items-center gap-2">
-							{#if config.icon}<MdiIcon name={config.icon} />{/if}
+							<span style="color: var(--color-primary);"><MdiIcon name={providerDefaultIcon({ icon: config.icon, type: config.provider_type })} size={20} /></span>
 							<p class="font-medium">{config.name}</p>
 							<span class="text-xs px-1.5 py-0.5 rounded bg-[var(--color-muted)] text-[var(--color-muted-foreground)] font-mono">{config.provider_type}</span>
 						</div>