War Bells v0.16.0

War Bells v0.16.0 — fixes Sheen (and the whole "builds to a wall" class).

Some presets (Sheen worst) slowly built up to the rails over several seconds of sustained playing —
a runaway my short tests missed. The output ceiling now firmly holds sustained washes so they settle
instead of climbing; every preset stays well off the rails (Sheen peak 0.99 -> 0.79). Also tightened
the shimmer/reverb feedback. And the test suite now runs a multi-second stability audit on every
preset, every build, so this can't slip through again.

Manual/demo: https://seajaysec.github.io/war-bells/