OnSpectrumReady/OnWaterfallReady move into TRadioController. The controller now
owns the last spectrum/waterfall frame (FSpectrumBuf/FWaterfallBuf) for the web
mirror and emits raw pixels via OnSpectrumData/OnWaterfallData. MainForm
subscribes for FSpecView rendering (+ waterfall scroll decimation, a UI concern).
TWebAdapter.PushState now reads the frame from the controller (no buffer params).
Behavior-preserving; removes the last spectrum/waterfall data-path coupling.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
