Let system dialogs take clicks during capture; hint Esc on the overlay

The event tap consumes every click while selecting, which made permission
prompts unclickable when they appeared mid-capture. Clicks now pass
through when a system dialog (SecurityAgent / System Settings) is
frontmost, and the overlay shows a visible Esc hint as an escape hatch.

💘 Generated with Crush

Assisted-by: Crush:deepseek-v4-flash-0731

Sources/Kapture/OverlayView.swift

@@ -57,6 +57,23 @@ final class OverlayView: NSView {
         NSColor.black.withAlphaComponent(0.35).setFill()
         NSBezierPath(rect: bounds).fill()
 
+        // Esc hint — the only way out once clicks are consumed by the tap.
+        let hint = "Drag to select · hover + click a window to capture it · Esc to cancel"
+        let hintAttrs: [NSAttributedString.Key: Any] = [
+            .font: NSFont.monospacedSystemFont(ofSize: 12, weight: .medium),
+            .foregroundColor: NSColor.white.withAlphaComponent(0.85),
+        ]
+        let hintSize = hint.size(withAttributes: hintAttrs)
+        let hintRect = NSRect(
+            x: (bounds.width - hintSize.width) / 2 - 10,
+            y: bounds.height - 46,
+            width: hintSize.width + 20,
+            height: hintSize.height + 12
+        )
+        NSColor.black.withAlphaComponent(0.65).setFill()
+        NSBezierPath(roundedRect: hintRect, xRadius: 8, yRadius: 8).fill()
+        hint.draw(at: NSPoint(x: hintRect.minX + 10, y: hintRect.minY + 6), withAttributes: hintAttrs)
+
         guard let controller else { return }
 
         // Highlight the hovered window (rounded, like real window corners)