Play LV2 instruments when qualifying them: MIDI through the atom port under the interposer #77

What is missing. The CLAP prober now plays a plugin with a note input under a count of its own (#72, the note sweep). The LV2 measurer (native/lv2-measure.c) still feeds no MIDI: an LV2 synth that allocates on note on reads clean, and git grep -n midi native/ finds no feed.

Where it plugs in. lv2-measure.c's rt-safety arm: for a plugin with an atom:AtomPort input supporting midi:MidiEvent, a sequence buffer per block carrying the same pattern as the CLAP sweep (note_block in native/clap-qualify.c: chord, bend and a controller, pressure, chord off, a burst of 32 note ons, their offs, all notes off), counted apart; the document's rtSafety block gains the same noteSweep shape.

Done when. An LV2 fixture instrument that calls malloc on note on is unsuitable and the same fixture without it suitable (sabotage pair), and an effect's verdict is unchanged.