Fix 16-bar pad dropout: don't re-swell established voices on live-loop re-entry

Repro (seed 70277 journey, sf=minimoog): pads dropped to ~0.28 of full every form cycle (~16-18 bars). Root cause (measured, not assumed

• Fix (live-path only): makeWalk gains per-voice loop memory — an established voice (whose run has ended at least once, incl. across the loop seam) re-enters at FULL via _voiceRun[v].noIn

• Byte-safe: press/offline never sets _voiceRun, so fixtures are byte-stable (3861 hashes, NO recapture); matrix 249/249, segment-parity byte-equal, wavout-seam + verify.sh PASS.

▶ Play it: Highway Heat Death — where the synthesis is the identity, not the decoration https://stellate.app/?genre=synthwave&seed=2161&path=859.9909,878.9942,840.9942&xdur=13.122

0fd2d07 https://github.com/aboard-io/stellate/commit/0fd2d071d8d1b0072bab52dc8f1600c35c82b56f