irisify v0.4.0 - stable flash rendering + border-hugging glow

fix: ResizeObserver re-render loop that caused page-height jitter and
  flashing in Chrome - clip the oversized rotating flash conic so it can't
  leak into document scroll, and skip resize notifications that don't change
  the integer border-box.
fix: restore the flash wedge's fading trailing end (a hard solid cut crept in
  with the transform-rotate sweep) and lengthen the line-end taper so both
  ends of the lit arc dissolve smoothly.
change: outer glow now hugs the border - wider and softer, with no detached
  floating clouds. Fully overridable via `intensity`,
  `advanced.outerGlowBlur`, and `advanced.outerGlowOpacity`.

irisify v0.3.2 - iridescent border glow for any element

Custom flash directions now auto-route: any non-default flashOriginAngle /
flashDestAngle switches to the JS two-arm engine on its own, so origin/dest
just work without also setting flashAxis. The pure-CSS conic is kept only for
the canonical bottom-to-top flash (zero animation loop, pixel-identical to the
original). flashAxis remains as an explicit escape hatch.