fix(ui): shrink-wrap floating player bar instead of full-width strip (#969)

* fix(ui): shrink-wrap floating player bar instead of full-width strip

The bar used fixed left and right insets, which stretched its background
across the whole main column. Center it with max-content width so only
the pill-shaped controls are painted, and soften the drop shadow.

* docs: note PR #969 in changelog and settings credits

src/styles/layout/_intro.css

@@ -40,3 +40,7 @@
     "sidebar main queue";
 }
 
+.app-shell.floating-player .resizer {
+  bottom: 0;
+}
+

src/styles/layout/player-bar.css

@@ -21,19 +21,18 @@
 .player-bar.floating {
   position: fixed;
   bottom: 12px;
-  /* left/right handled dynamically by JS */
+  /* left / max-width set by useFloatingPlayerBar — center + shrink-wrap */
   z-index: 1000;
   border-radius: 50px;
-  width: auto;
-  min-width: 100px;
-  max-width: none;
+  width: max-content;
+  max-width: min(100%, calc(100vw - 48px));
   grid-area: unset;
   padding: 0 24px 0 8px;
   gap: 16px;
   background: var(--bg-player);
   border: 1px solid rgba(255, 255, 255, 0.12);
   box-shadow:
-    0 8px 32px rgba(0, 0, 0, 0.8),
+    0 8px 32px rgba(0, 0, 0, 0.45),
     0 0 0 1px rgba(255, 255, 255, 0.05),
     inset 0 1px 0 rgba(255, 255, 255, 0.08);
 }