[paulirish]

Fixes #352 (and #327 along the way).

Swaps @acemir/cssom for cssomnom/parse and backs el.style (esm/interface/css-style-declaration.js) with cssomnom's CSSStyleDeclaration + onChange hook so el.style and sheet.cssRules[i].style share the same implementation (and we can drop the uhyphen dep).

What this changes:

• Pure ESM with standard exports, so Vite/Rolldown/esbuild browser and worker builds resolve cleanly.
• el.style.toString() / cssText now serializes per the CSSOM spec (#serialize-a-css-declaration-block) with canonical spacing and trailing semicolon ("background-color: blue; ...;" instead of "background-color:blue;..."), matching browsers and sheet.cssRules[i].style, as @lppedd noted in 0.18.14: browser bundlers fail with "parse" is not exported by @acemir/cssom/build/CSSOM.js #352.
• Setting el.style.color = '' removes the property instead of leaving color: ; in the attribute (fixes el.style.property = '' and e.style.setProperty('property', '') should delete the property #327).
• url("data:image/svg+xml;utf8,...") values containing ; or : no longer get split across declarations, and --customProperty preserves case.

If you'd rather keep esm/interface/css-style-declaration.js untouched for now so el.style.toString() formatting stays identical and only swap esm/html/style-element.js, here's what that minimal diff looks like (happy to drop the last commit if you prefer that!). :)