fix: keep initial playback focus off the titlebar pin

Restore the playback window as first responder after initial setup and after file/YouTube dialogs return. Keep native control focus indicators and Tab navigation unchanged.

Verified hidden native window focus, both dialog cancellations, explicit control focus, Tab navigation, P shortcut, app build, and compact-window checks.

Sources/App/TerebiApp.swift

@@ -85,6 +85,7 @@ final class PlayerModel: ObservableObject {
 
     func openPanel() {
         guard canOpen else { return }
+        defer { window?.makeFirstResponder(nil) }
         revealControls()
         let panel = NSOpenPanel()
         panel.canChooseFiles = true
@@ -97,6 +98,7 @@ final class PlayerModel: ObservableObject {
 
     func openYouTubePanel() {
         guard canOpen else { return }
+        defer { window?.makeFirstResponder(nil) }
         revealControls()
         let alert = NSAlert()
         alert.messageText = "Open YouTube Video"
@@ -1030,6 +1032,7 @@ private struct WindowChrome: NSViewRepresentable {
                 guard let self, let window else { return }
                 self.model.attachWindow(window)
                 self.updateButtons()
+                window.makeFirstResponder(nil)
             }
         }