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/add.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1024 1024"><path d="M861.541 469.516h-307.058v-307.058c0-23.464-19.020-42.484-42.484-42.484-23.463 0-42.484 19.020-42.484 42.484v307.058h-307.058c-23.464 0-42.484 19.020-42.484 42.484 0 23.463 19.020 42.484 42.484 42.484h307.058v307.058c0 23.463 19.020 42.484 42.484 42.484 23.463 0 42.484-19.021 42.484-42.484v-307.058h307.058c23.463 0 42.484-19.020 42.484-42.484-0.001-23.463-19.022-42.484-42.485-42.484z"></path></svg>