Corrects theme.h's large-text thresholds, names accent/secondary's real
binding limiter, and adds compositeOver so the loop-span fill's 2.25:1
under-floor pair is asserted rather than assumed.
Decouples the keyboard strip's mid stop from accent/secondary, which the
deep-teal darkening had inverted. Adds overlay/trace (#816AA6), the first
value to clear 3:1 against the waveform. Replaces the frozen-premise test.