Add a top menu bar (host/src/ui/app_chrome) as the overlay shell:
- View menu toggles each panel (Controllers / Injection / Video / Audio)
and a global "Debug details" switch (consumed by panels in a follow-up).
- A right-aligned performance readout: stable 1 s FPS plus the frame-time
spread (avg, min-max) so stutter is visible; it turns amber on a >25 ms
spike. FrameStats keeps the rolling window.
Consolidates the FPS that was duplicated in the controllers and video
panels into this one readout.
First structural step of the "generalize the UI" roadmap task; content
rework (debug-vs-general split, renaming the spike-era readouts) follows.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>