fix(ui): close more gaps with mockup (tabs, mini player, volume control)

Tabs
- Replace SVG icons with mockup-style numeric badges (01..05)
- Hide the legacy .tab-indicator (was rendering as a long copper
  bar above the strip); active tab gets its own copper underline
  via .tab-btn.active::after
- Numbers turn copper on the active tab

Player view
- Volume control restored: mute button + slim copper slider live
  inside the VU cluster, on the right of the readout, separated
  by a hairline. Slider is the existing #volume-slider so all JS
  hooks (bidirectional sync, drag, etc.) keep working.
- Track title font scaled down (clamp 34..64) and clamped to 3
  lines with ellipsis so long YouTube-style titles don't dominate
  the masthead. Adds word-break + overflow-wrap.
- #artist:empty and #album:empty are now display:none so blank
  rows don't leave a gap when the source provides no metadata.

Mini player
- Forced display: grid with 4 columns: track / controls / progress
  / volume. Was inheriting legacy display:flex which pushed elements
  into a single non-aligned row.
- Position locked: position: fixed, bottom: 0, left/right: 0 with
  !important. The strip is firmly anchored to the viewport bottom.
- Top edge progress (::before) painted in copper with glow.
- Responsive collapse: hide progress at <=880px, hide volume at
  <=540px, leaving track + controls on phones.

i18n
- tab.player default text aligned to "Now Spinning" (matches
  existing en/ru values added earlier).

media_server/static/index.html

@@ -131,27 +131,27 @@
             <button class="connection-banner-btn" id="connectionBannerBtn" onclick="manualReconnect()" style="display: none;" data-i18n="connection.reconnect">Reconnect</button>
         </div>
 
-        <!-- Tab Bar -->
+        <!-- Tab Bar (editorial: numbered, italic active) -->
         <div class="tab-bar" id="tabBar" role="tablist">
             <div class="tab-indicator" id="tabIndicator"></div>
             <button class="tab-btn active" data-tab="player" onclick="switchTab('player')" role="tab" aria-selected="true" aria-controls="panel-player" tabindex="0">
-                <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M12 3v10.55c-.59-.34-1.27-.55-2-.55-2.21 0-4 1.79-4 4s1.79 4 4 4 4-1.79 4-4V7h4V3h-6z"/></svg>
-                <span data-i18n="tab.player">Player</span>
+                <span class="tab-num">01</span>
+                <span data-i18n="tab.player">Now Spinning</span>
             </button>
             <button class="tab-btn" data-tab="display" onclick="switchTab('display')" role="tab" aria-selected="false" aria-controls="panel-display" tabindex="-1">
-                <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M20 3H4c-1.1 0-2 .9-2 2v10c0 1.1.9 2 2 2h6v2H8v2h8v-2h-2v-2h6c1.1 0 2-.9 2-2V5c0-1.1-.9-2-2-2zm0 12H4V5h16v10z"/></svg>
+                <span class="tab-num">02</span>
                 <span data-i18n="tab.display">Display</span>
             </button>
             <button class="tab-btn" data-tab="browser" onclick="switchTab('browser')" role="tab" aria-selected="false" aria-controls="panel-browser" tabindex="-1">
-                <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M10 4H4c-1.1 0-2 .9-2 2v12c0 1.1.9 2 2 2h16c1.1 0 2-.9 2-2V8c0-1.1-.9-2-2-2h-8l-2-2z"/></svg>
-                <span data-i18n="tab.browser">Browser</span>
+                <span class="tab-num">03</span>
+                <span data-i18n="tab.browser">Library</span>
             </button>
             <button class="tab-btn" data-tab="quick-actions" onclick="switchTab('quick-actions')" role="tab" aria-selected="false" aria-controls="panel-quick-actions" tabindex="-1">
-                <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M7 2v11h3v9l7-12h-4l4-8z"/></svg>
+                <span class="tab-num">04</span>
                 <span data-i18n="tab.quick_access">Quick Access</span>
             </button>
             <button class="tab-btn" data-tab="settings" onclick="switchTab('settings')" role="tab" aria-selected="false" aria-controls="panel-settings" tabindex="-1">
-                <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M19.14 12.94c.04-.3.06-.61.06-.94 0-.32-.02-.64-.07-.94l2.03-1.58a.49.49 0 00.12-.61l-1.92-3.32a.488.488 0 00-.59-.22l-2.39.96c-.5-.38-1.03-.7-1.62-.94l-.36-2.54a.484.484 0 00-.48-.41h-3.84c-.24 0-.43.17-.47.41l-.36 2.54c-.59.24-1.13.57-1.62.94l-2.39-.96c-.22-.08-.47 0-.59.22L2.74 8.87c-.12.21-.08.47.12.61l2.03 1.58c-.05.3-.07.62-.07.94s.02.64.07.94l-2.03 1.58a.49.49 0 00-.12.61l1.92 3.32c.12.22.37.29.59.22l2.39-.96c.5.38 1.03.7 1.62.94l.36 2.54c.05.24.24.41.48.41h3.84c.24 0 .44-.17.47-.41l.36-2.54c.59-.24 1.13-.56 1.62-.94l2.39.96c.22.08.47 0 .59-.22l1.92-3.32c.12-.22.07-.47-.12-.61l-2.01-1.58zM12 15.6c-1.98 0-3.6-1.62-3.6-3.6s1.62-3.6 3.6-3.6 3.6 1.62 3.6 3.6-1.62 3.6-3.6 3.6z"/></svg>
+                <span class="tab-num">05</span>
                 <span data-i18n="tab.settings">Settings</span>
             </button>
         </div>
@@ -247,7 +247,7 @@
                                 <svg viewBox="0 0 24 24"><path d="M6 18l8.5-6L6 6v12zM16 6v12h2V6h-2z"/></svg>
                             </button>
 
-                            <div class="vu-cluster" onclick="toggleMute()" title="Click to mute / use mini player to adjust volume" role="button" tabindex="0">
+                            <div class="vu-cluster">
                                 <div class="vu-meter" aria-hidden="true">
                                     <div class="vu-needle" id="vuNeedle"></div>
                                 </div>
@@ -255,19 +255,21 @@
                                     <span>OUT <strong id="vu-out">SYS</strong></span>
                                     <span>VOL <strong id="vu-vol">50%</strong></span>
                                 </div>
+                                <!-- Volume control: mute + slim slider, integrated -->
+                                <div class="vu-volume">
+                                    <button class="mute-btn" onclick="toggleMute()" data-i18n-title="player.mute" title="Mute" id="btn-mute">
+                                        <svg viewBox="0 0 24 24" id="mute-icon">
+                                            <path d="M3 9v6h4l5 5V4L7 9H3zm13.5 3c0-1.77-1.02-3.29-2.5-4.03v8.05c1.48-.73 2.5-2.25 2.5-4.02z"/>
+                                        </svg>
+                                    </button>
+                                    <input type="range" id="volume-slider" min="0" max="100" value="50" aria-label="Volume">
+                                </div>
                             </div>
                         </div>
                     </div>
 
-                    <!-- Hidden but functional: slider + mute + visualizer toggle.
-                         Adjustment happens via the always-visible mini player. -->
+                    <!-- Hidden but functional: legacy display + visualizer toggle. -->
                     <div class="visually-hidden">
-                        <button class="mute-btn" onclick="toggleMute()" data-i18n-title="player.mute" title="Mute" id="btn-mute">
-                            <svg viewBox="0 0 24 24" id="mute-icon">
-                                <path d="M3 9v6h4l5 5V4L7 9H3zm13.5 3c0-1.77-1.02-3.29-2.5-4.03v8.05c1.48-.73 2.5-2.25 2.5-4.02z"/>
-                            </svg>
-                        </button>
-                        <input type="range" id="volume-slider" min="0" max="100" value="50" aria-label="Volume">
                         <div id="volume-display">50%</div>
                         <button onclick="toggleVisualizer()" id="visualizerToggle" data-i18n-title="player.visualizer" title="Audio visualizer" style="display:none">
                             <svg viewBox="0 0 24 24" width="16" height="16"><path fill="currentColor" d="M3 18h2v-8H3v8zm4 0h2V6H7v12zm4 0h2V2h-2v16zm4 0h2v-6h-2v6zm4 0h2V9h-2v9z"/></svg>