fix(a11y): add aria-hidden to all decorative SVG icon components (#21705)

Add aria-hidden='true' to 112 SVG icon components in src/lib/components/icons/ that were missing this attribute. Decorative icons that convey no semantic meaning should be hidden from the accessibility tree to prevent screen readers from attempting to read meaningless SVG markup (WCAG 1.1.1 Non-text Content, WCAG 4.1.2 Name, Role, Value).

The remaining 60 icon files already had aria-hidden='true' set. All 172 icon components now consistently declare aria-hidden='true' on their root svg element.

src/lib/components/icons/UserAlt.svelte

@@ -4,6 +4,7 @@
 </script>
 
 <svg
+	aria-hidden="true"
 	stroke-width={strokeWidth}
 	viewBox="0 0 24 24"
 	xmlns="http://www.w3.org/2000/svg"