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/v2-split-panel-layout/config-panels/SharedComponents.tsx

@@ -37,14 +37,14 @@ export function SortableColumnRow({
       className={cn(
         "flex items-center gap-1.5 rounded-md border bg-card px-2 py-1.5",
         isDragging && "z-50 opacity-50 shadow-md",
-        isEntityJoin && "border-blue-200 bg-blue-50/30",
+        isEntityJoin && "border-primary/20 bg-primary/10/30",
       )}
     >
       <div {...attributes} {...listeners} className="text-muted-foreground hover:text-foreground cursor-grab touch-none">
         <GripVertical className="h-3 w-3" />
       </div>
       {isEntityJoin ? (
-        <Link2 className="h-3 w-3 shrink-0 text-blue-500" title="Entity 조인 컬럼" />
+        <Link2 className="h-3 w-3 shrink-0 text-primary" title="Entity 조인 컬럼" />
       ) : (
         <span className="text-muted-foreground w-5 shrink-0 text-center text-[10px] font-medium">#{index + 1}</span>
       )}