feat: add graceful degradation and conditional favorites filter

Add progressive enhancement to hide filter panel when JavaScript is
disabled, and conditionally render favorites filter based on login status.

Search Component:
- Added showFilters state (default false)
- Set showFilters to true in onMount when JS is enabled
- Wrapped FilterPanel in {#if showFilters} for graceful degradation
- Filters hidden without JavaScript, visible with JS

FilterPanel:
- Split grid layout into two variants:
  - with-favorites: 5 columns (120px 120px 1fr 160px 90px)
  - without-favorites: 4 columns (120px 120px 1fr 160px)
- Conditionally render FavoritesFilter only when isLoggedIn
- Apply appropriate class based on login status

FavoritesFilter:
- Simplified template (no internal login check)
- Only rendered when user is logged in via FilterPanel

UX:
- Non-JS browsers: Simple search only, filters gracefully hidden
- Not logged in: 4-column layout without favorites filter
- Logged in: 5-column layout with favorites filter

src/lib/components/FavoritesFilter.svelte

@@ -10,8 +10,7 @@
 	} = $props();
 
 	const isEnglish = $derived(lang === 'en');
-	const label = $derived(isEnglish ? 'Favorites Only' : 'Nur Favoriten');
-	const loginRequiredLabel = $derived(isEnglish ? 'Login required' : 'Anmeldung erforderlich');
+	const label = $derived(isEnglish ? 'Favorites' : 'Favoriten');
 
 	let checked = $state(enabled);
 
@@ -57,24 +56,13 @@
 			text-align: left;
 		}
 	}
-
-	.login-required {
-		font-size: 0.85rem;
-		color: var(--nord3);
-		font-style: italic;
-		padding: 0.5rem 0;
-	}
 </style>
 
 <div class="filter-section">
 	<div class="filter-label">{label}</div>
-	{#if isLoggedIn}
-		<Toggle
-			bind:checked={checked}
-			label=""
-			on:change={handleChange}
-		/>
-	{:else}
-		<div class="login-required">{loginRequiredLabel}</div>
-	{/if}
+	<Toggle
+		bind:checked={checked}
+		label=""
+		on:change={handleChange}
+	/>
 </div>

src/lib/components/FilterPanel.svelte

@@ -79,11 +79,18 @@
 
 	.filter-panel {
 		display: grid;
-		grid-template-columns: 120px 120px 1fr 160px 140px;
 		gap: 2rem;
 		align-items: start;
 	}
 
+	.filter-panel.with-favorites {
+		grid-template-columns: 120px 120px 1fr 160px 90px;
+	}
+
+	.filter-panel.without-favorites {
+		grid-template-columns: 120px 120px 1fr 160px;
+	}
+
 	@media (max-width: 968px) {
 		.toggle-button {
 			display: flex;
@@ -125,7 +132,7 @@
 		<span class="arrow" class:open={filtersOpen}>▼</span>
 	</button>
 
-	<div class="filter-panel" class:open={filtersOpen}>
+	<div class="filter-panel" class:open={filtersOpen} class:with-favorites={isLoggedIn} class:without-favorites={!isLoggedIn}>
 		<CategoryFilter
 			categories={availableCategories}
 			selected={selectedCategory}
@@ -154,11 +161,13 @@
 			{months}
 		/>
 
-		<FavoritesFilter
-			enabled={selectedFavoritesOnly}
-			onToggle={onFavoritesToggle}
-			{isLoggedIn}
-			{lang}
-		/>
+		{#if isLoggedIn}
+			<FavoritesFilter
+				enabled={selectedFavoritesOnly}
+				onToggle={onFavoritesToggle}
+				{isLoggedIn}
+				{lang}
+			/>
+		{/if}
 	</div>
 </div>

src/lib/components/Search.svelte

@@ -27,6 +27,7 @@
     });
 
     let searchQuery = $state('');
+    let showFilters = $state(false);
 
     // Filter data loaded from APIs
     let availableTags = $state([]);
@@ -246,6 +247,9 @@
             clearButton.style.display = 'flex';
         }
 
+        // Enable filter panel for JS-enabled browsers
+        showFilters = true;
+
         // Get initial search value from URL if present
         const urlParams = new URLSearchParams(window.location.search);
         const urlQuery = urlParams.get('q');
@@ -340,20 +344,22 @@ scale: 0.8 0.8;
   </button>
 </form>
 
-<FilterPanel
-  availableCategories={categories}
-  {availableTags}
-  {availableIcons}
-  {selectedCategory}
-  {selectedTags}
-  {selectedIcon}
-  {selectedSeasons}
-  {selectedFavoritesOnly}
-  {lang}
-  {isLoggedIn}
-  onCategoryChange={handleCategoryChange}
-  onTagToggle={handleTagToggle}
-  onIconChange={handleIconChange}
-  onSeasonChange={handleSeasonChange}
-  onFavoritesToggle={handleFavoritesToggle}
-/>
+{#if showFilters}
+  <FilterPanel
+    availableCategories={categories}
+    {availableTags}
+    {availableIcons}
+    {selectedCategory}
+    {selectedTags}
+    {selectedIcon}
+    {selectedSeasons}
+    {selectedFavoritesOnly}
+    {lang}
+    {isLoggedIn}
+    onCategoryChange={handleCategoryChange}
+    onTagToggle={handleTagToggle}
+    onIconChange={handleIconChange}
+    onSeasonChange={handleSeasonChange}
+    onFavoritesToggle={handleFavoritesToggle}
+  />
+{/if}