preserve `ti-fw` classes for icons - fixes #580

I thought that `ti-fw` was mostly useless, but it turns out that:

- it affects the alignment of icons in many places

- it's set separately in some places
  (e.g. `packages/frontend/src/ui/_common_/navbar.ts` has `<i
  class="ti-fw" :class="[$style.itemIcon,
  navbarItemDef[item].icon]"></i>`)

so we have to keep it around.

packages/frontend/vite.replaceIcons.ts

@@ -5,10 +5,9 @@ function iconsReplace(opts: RollupReplaceOptions) {
 	return pluginReplace({
 		...opts,
 		preventAssignment: false,
-		// only replace these strings at the start of strings, remove a
-		// `ti-fw` it if happens to be just after, and make sure they're
-		// followed by a word-boundary that's not a dash
-		delimiters: ['(?<=["\'`])', '(?: ti-fw)?\\b(?!-)'],
+		// only replace these strings at the start of strings, and make
+		// sure they're followed by a word-boundary that's not a dash
+		delimiters: ['(?<=["\'`])', '\\b(?!-)'],
 	});
 }