fix: clip frosted backdrop to rounded panel bounds

Sources/Conjure/LauncherWindowController.swift

@@ -61,9 +61,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         content.material = .hudWindow
         content.blendingMode = .behindWindow
         content.state = .active
-        content.wantsLayer = true
-        content.layer?.cornerRadius = 24
-        content.layer?.masksToBounds = true
+        roundMaterialCorners(content, radius: 24)
         content.layer?.borderWidth = 0.5
         window.contentView = content
         let background = LauncherBackground(frame: content.bounds)
@@ -164,9 +162,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         actionPill.material = .popover
         actionPill.blendingMode = .withinWindow
         actionPill.state = .active
-        actionPill.wantsLayer = true
-        actionPill.layer?.cornerRadius = 18
-        actionPill.layer?.masksToBounds = true
+        roundMaterialCorners(actionPill, radius: 18)
         actionPill.layer?.borderWidth = 0.5
         for view in [openButton, returnKey] {
             view.translatesAutoresizingMaskIntoConstraints = false
@@ -432,3 +428,19 @@ private final class LauncherRowView: NSTableRowView {
         selection.stroke()
     }
 }
+
+@MainActor
+private func roundMaterialCorners(_ view: NSVisualEffectView, radius: CGFloat) {
+    let size = NSSize(width: radius * 2 + 1, height: radius * 2 + 1)
+    let mask = NSImage(size: size, flipped: false) { rect in
+        NSColor.black.setFill()
+        NSBezierPath(roundedRect: rect, xRadius: radius, yRadius: radius).fill()
+        return true
+    }
+    mask.capInsets = NSEdgeInsets(top: radius, left: radius, bottom: radius, right: radius)
+    mask.resizingMode = .stretch
+    view.wantsLayer = true
+    view.layer?.cornerRadius = radius
+    view.layer?.masksToBounds = true
+    view.maskImage = mask
+}