Mixer, per-voice insert FX as vector dimensions, automated fills

mixer modal: 10 layer taps/meters/faders/mute-solo; buried-vs-absent answered at a glance (not-in-this-section state)

• insert FX dimension: distort/phaser/chorus/filtersweep pools on ~32 anchors, blended + constrained like every dimension; kernel emits instruments.*.inserts

• fills: 100% of major section boundaries filled, seeded no-repeat, 3 new flavors (snare roll, stutter gate, dropout); genre-curated

Verified: matrix 61/61, validate PASS, ab regression md5-identical, live load >=0.97 with inserts + mixer

▶ Play it: Perforated Afterlife — the anchor authored from a measured corpus of real melodies https://stellate.app/?genre=ragtime&seed=8522&path=753.14435,772.14468,734.14468&xdur=13.122

954fe28 https://github.com/aboard-io/stellate/commit/954fe28a4aea46cf662376d6e42ca3eb5f1dd2fc