Add browser search/filter for media items

- Search bar appears when browsing inside a folder
- Client-side filtering with 200ms debounce
- Clear button and search icon
- Hides at root level, resets on navigation
- Localized placeholder (en/ru)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

media_server/static/css/styles.css

@@ -1261,6 +1261,68 @@
     gap: 0.75rem;
 }
 
+/* Browser Search */
+.browser-search-wrapper {
+    flex: 1;
+    position: relative;
+    min-width: 0;
+    max-width: 300px;
+}
+
+.browser-search-icon {
+    position: absolute;
+    left: 0.6rem;
+    top: 50%;
+    transform: translateY(-50%);
+    color: var(--text-muted);
+    pointer-events: none;
+}
+
+.browser-search-input {
+    width: 100%;
+    padding: 0.4rem 2rem 0.4rem 2rem;
+    background: var(--bg-tertiary);
+    border: 1px solid var(--border);
+    border-radius: 6px;
+    color: var(--text-primary);
+    font-size: 0.813rem;
+    outline: none;
+    transition: border-color 0.2s;
+}
+
+.browser-search-input:focus {
+    border-color: var(--accent);
+}
+
+.browser-search-input::placeholder {
+    color: var(--text-muted);
+}
+
+.browser-search-clear {
+    position: absolute;
+    right: 0.4rem;
+    top: 50%;
+    transform: translateY(-50%);
+    background: none;
+    border: none;
+    color: var(--text-muted);
+    cursor: pointer;
+    padding: 0.15rem;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 50%;
+    width: auto;
+    height: auto;
+    transition: color 0.15s;
+}
+
+.browser-search-clear:hover {
+    color: var(--text-primary);
+    background: transparent !important;
+    transform: translateY(-50%) !important;
+}
+
 .view-toggle {
     display: flex;
     background: var(--bg-tertiary);
@@ -1853,6 +1915,10 @@
         align-items: stretch;
     }
 
+    .browser-search-wrapper {
+        max-width: none;
+    }
+
     .browser-toolbar-right {
         justify-content: flex-end;
     }