fix(ui): drop redundant Elapsed/Length cells; restore timeline

- Meta-grid reduced from 4 cells to 2 (State / Source). Elapsed and
  Length were duplicates of the timecodes already flanking the
  timeline. Added .meta-grid-2 modifier with a 2-column layout.
- Timeline was distorted by legacy rules: .progress-bar:hover did
  scaleY(1.4) (inflating the 2px hairline on hover) and the
  progress-fill::after handle defaulted to scale(0). Both are now
  forced via !important to keep the hairline flat and the copper
  handle always visible.
- progress-row uses minmax(0, 1fr) for the bar cell so it shrinks
  cleanly inside the grid.
- Removed unused meta.elapsed / meta.length keys from en.json + ru.json.
- Dead JS lookups for #meta-elapsed / #meta-length stay (cheap if-checks,
  no-op when DOM elements gone).

media_server/static/index.html

@@ -198,8 +198,8 @@
                         <div id="album"></div>
                     </div>
 
-                    <!-- Editorial metadata grid (4 cells) -->
-                    <div class="meta-grid">
+                    <!-- Editorial metadata grid (State + Source; timecodes are on the timeline) -->
+                    <div class="meta-grid meta-grid-2">
                         <div class="meta-cell">
                             <div class="meta-label" data-i18n="meta.state">State</div>
                             <div class="meta-value">
@@ -216,14 +216,6 @@
                                 <span id="source" data-i18n="player.unknown_source">Unknown</span>
                             </div>
                         </div>
-                        <div class="meta-cell">
-                            <div class="meta-label" data-i18n="meta.elapsed">Elapsed</div>
-                            <div class="meta-value mono" id="meta-elapsed">0:00</div>
-                        </div>
-                        <div class="meta-cell">
-                            <div class="meta-label" data-i18n="meta.length">Length</div>
-                            <div class="meta-value mono" id="meta-length">0:00</div>
-                        </div>
                     </div>
 
                     <!-- Decorative spectrum bars -->