Builder overhaul: fix silent drums, per-instrument synths, swing/humanize, vaporwave UI

Major fix:

• DRUMS WERE SILENT — instr 10/11/12 read amp from p5 but the score passes it in p4. Fixed in both csd-engine.js and royal-road.csd (drums-only render now peaks 0.71 vs 0.00; royal-road.csd peak 0.31 -> 0.67).

• Removed the solo/chords section type; every section is uniform, found sound is just another (off-by-default) layer instead of forced on every row.

• Compacted rows; drag ⠿ to reorder sections.

• Per-instrument synth editors (click an instrument header): waveform (sine/saw/square/pulse), cutoff, resonance, detune, attack, vibrato, level, reverb send — all wired into a parameterized orchestra.

▶ Play it: Food Court Eternity — parked on the genre this change names https://stellate.app/?genre=vaporwave&seed=2928&path=1679.4393,1698.4426,1660.4426&xdur=13.122

848cad5 https://github.com/aboard-io/stellate/commit/848cad58ff51dda92248f3874ec5c5bba59a9b6c