refactor: 전체 프론트엔드 하드코딩 색상 → CSS 변수 일괄 치환

447+ 파일, 4500+ 줄 변경:
- gray-* → border/bg-muted/text-foreground/text-muted-foreground
- blue-* → primary/ring
- red-* → destructive
- green-* → emerald (일관성)
- indigo-* → primary
- yellow/orange → amber (통일)
- dark mode 변형도 시맨틱 토큰으로 변환

Made-with: Cursor

frontend/lib/registry/components/entity-search-input/EntitySearchModal.tsx

@@ -187,7 +187,7 @@ export function EntitySearchModal({
                         key={uniqueKey}
                         className={cn(
                           "border-t cursor-pointer transition-colors",
-                          isSelected ? "bg-blue-50 hover:bg-blue-100" : "hover:bg-accent"
+                          isSelected ? "bg-primary/10 hover:bg-primary/10" : "hover:bg-accent"
                         )}
                         onClick={() => handleSelect(item)}
                       >