fix: preserve video aspect ratio while resizing queue window

Checks/system-playback.swift

@@ -326,6 +326,23 @@ struct SystemPlaybackChecks {
             model.setPointerInsideWindow(true)
         }
         until("open starts authoritative playback") { model.canTogglePlayback && model.state.status == PLAYER_PLAYING }
+        model.showsQueue = true
+        for delta in [NSSize(width: 160, height: 0), NSSize(width: 0, height: 90),
+                      NSSize(width: -100, height: 0), NSSize(width: 0, height: -60)] {
+            let proposal = NSSize(width: window.frame.width + delta.width, height: window.frame.height + delta.height)
+            guard let constrained = window.delegate?.windowWillResize?(window, to: proposal) else {
+                fatalError("FAIL: native resize delegate must constrain queue video geometry")
+            }
+            var frame = window.frame
+            frame.size = constrained
+            window.setFrame(frame, display: true)
+            let content = window.contentRect(forFrameRect: window.frame)
+            require(abs((content.width - 260) / content.height - model.state.video_aspect_ratio) < 0.001,
+                    "horizontal and vertical queue resizing preserves video aspect with fixed sidebar width")
+            require(delta.width == 0 ? abs(frame.height - proposal.height) < 1 : abs(frame.width - proposal.width) < 1,
+                    "aspect-locked queue window follows the dragged axis")
+        }
+        model.showsQueue = false
         require(center.playbackState == .playing, "playing publishes macOS playback ownership")
         requirePlaybackPower(system: true, display: true, "local video keeps the Mac and display awake")
         var bufferingState = model.state