🎨 Palette: [UX improvement] 장식용 아이콘에 aria-hidden 속성 추가

[seonghobae]

💡 What:
Added aria-hidden="true" to purely decorative SVG icons (from lucide-react) that are positioned directly next to descriptive text in the UI (specifically the <Download>, <Users>, <AlertCircle>, <Lightbulb>, and <Wand2> icons).

🎯 Why:
When a screen reader encounters an SVG icon without aria-hidden="true", it may announce the icon's default name followed by the adjacent descriptive text. For visually impaired users, this results in redundant and repetitive announcements, degrading the overall accessibility experience. Hiding purely decorative icons from screen readers makes the interface much cleaner to navigate.

📸 Before/After:
(Visual changes are unaffected. Screen reader output is improved).

♿ Accessibility:
Improves screen reader experience by silencing redundant SVG icons, making focus navigation and content reading more concise.

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PR created automatically by Jules for task 11193108891028147172 started by @seonghobae

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