The toolbar's keyboard icon used to toggle a custom function-key bar — it
never opened the iOS system keyboard, so users couldn't type into the remote.
Fix: FramebufferUIView now conforms to UIKeyInput + UITextInputTraits, so
becoming first responder presents the iOS keyboard. Tapping the keyboard
button toggles software-keyboard visibility on the framebuffer view via a
SwiftUI binding. While the keyboard is up, an inputAccessoryView toolbar
(esc / tab / ctrl / ⌘ / ⌥ / ←↓↑→ / dismiss) sits directly above it, with
each button forwarded to the existing controller.send… APIs.
The standalone SoftKeyboardBar overlay is no longer used.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>