fix(ui): prevent queue buttons from being pushed off-screen by long queue

Queue section now uses flex layout with flex-shrink:0 on action buttons,
so they stay visible regardless of queue list length.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/styles.css

@@ -172,6 +172,10 @@ body {
 .queue-section {
     border-top: 1px solid rgba(255,255,255,0.1);
     padding: 15px;
+    display: flex;
+    flex-direction: column;
+    min-height: 0;
+    flex: 1;
 }
 
 .queue-header {
@@ -196,8 +200,9 @@ body {
 }
 
 .queue-list {
-    max-height: 210px;
+    flex: 1;
     overflow-y: auto;
+    min-height: 60px;
 }
 
 .health-badge {
@@ -378,6 +383,7 @@ body {
     display: flex;
     gap: 8px;
     margin-top: 10px;
+    flex-shrink: 0;
 }
 
 .btn {