feat(icons): split built-in sprite into per-icon SVG sources and add ticket icon

Move the 114 built-in sprite icons out of assets/js/runtime/svg-icon.js into
assets/icons/sprite/{key}.svg and generate svg-icon.js with
tools/build-svg-sprite.mjs. Add ticket-color and use it for the user center
ticket entry. Update sidebar contract tests for the creator card labels.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/icons/sprite/left.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1024 1024"><path d="M704 908.8 307.2 512 704 115.2c25.6-25.6 25.6-70.4 0-96-25.6-25.6-70.4-25.6-96 0L166.4 460.8C147.2 480 140.8 492.8 140.8 512s6.4 32 19.2 51.2l441.6 441.6c25.6 25.6 70.4 25.6 96 0C729.6 979.2 729.6 934.4 704 908.8z" p-id="2034" data-spm-anchor-id="a313x.7781069.0.i4"></path></svg>