Add Play All, home navigation, and UI improvements

- Add Play All button with M3U playlist generation (local temp file with absolute paths)
- Replace folder combobox with root folder cards and home icon breadcrumb
- Fix compact grid card sizing (64x64 thumbnails, align-items: start)
- Add loading spinner when browsing folders
- Cache browse items to avoid re-fetching on view mode switch
- Remove unused browser-controls CSS
- Add localization keys for Play All and Home (en/ru)

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

media_server/static/index.html

@@ -147,13 +147,6 @@
         <div class="browser-container">
             <h2 data-i18n="browser.title">Media Browser</h2>
 
-            <!-- Folder Selection -->
-            <div class="browser-controls">
-                <select id="folderSelect" onchange="onFolderSelected()" data-i18n-empty="browser.select_folder">
-                    <option value="" data-i18n="browser.select_folder_option">Select a folder...</option>
-                </select>
-            </div>
-
             <!-- Breadcrumb Navigation -->
             <div class="breadcrumb" id="breadcrumb"></div>
 
@@ -171,6 +164,10 @@
                             <svg viewBox="0 0 24 24" width="18" height="18"><path d="M3 4h18v2H3V4zm0 7h18v2H3v-2zm0 7h18v2H3v-2z"/></svg>
                         </button>
                     </div>
+                    <button class="browser-play-all-btn" id="playAllBtn" onclick="playAllFolder()" data-i18n-title="browser.play_all" title="Play All" style="display: none;">
+                        <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M8 5v14l11-7z"/></svg>
+                        <span data-i18n="browser.play_all">Play All</span>
+                    </button>
                 </div>
                 <div class="browser-toolbar-right">
                     <label class="items-per-page-label">