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/CaptureController.swift

@@ -262,9 +262,21 @@ final class CaptureController: NSObject {
         return nil
     }
 
+    /// System dialogs (permission prompts, System Settings) must always
+    /// receive their clicks even while we're selecting.
+    private func isSystemDialogFrontmost() -> Bool {
+        guard let front = NSWorkspace.shared.frontmostApplication else { return false }
+        let id = front.bundleIdentifier ?? ""
+        return id.hasPrefix("com.apple.security") || id.hasPrefix("com.apple.SystemSettings") || id == "com.apple.systempreferences"
+    }
+
     /// Returns the event to pass through, or nil to consume it.
     func handleTap(_ type: CGEventType, _ event: CGEvent) -> CGEvent? {
         guard isSelecting else { return event }
+        if isSystemDialogFrontmost() {
+            CaptureController.log("tap: system dialog frontmost — passing through \(type)")
+            return event
+        }
 
         switch type {
         case .tapDisabledByUserInput, .tapDisabledByTimeout: