style(테이블타입): 탭 스타일 Google 식 underline 으로 변경 — 가시성 ↑

기존 shadcn 기본 Tabs 가 둥근 알약 (segmented control) 스타일이라 탭이 아니라 토글처럼
보임. 사용자가 "탭이 눈에 잘 안 띈다" 지적.

Gmail/Drive/GitHub/Vercel 공통 패턴인 underline 스타일로 변경:
- TabsList: 전체 폭 + 하단 1px 구분선, 배경/padding 제거
- TabsTrigger: 평면 + 활성 시 2px primary 밑줄 + 글자 색 강조, 비활성은 muted
- 글자 / 아이콘 크기 한 단계 ↑ (text-xs→text-sm, h-3.5→h-4)
- 비활성에도 transparent border-b-2 줘서 layout shift 방지

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/app/(main)/admin/systemMng/tableMngList/page.tsx

@@ -1695,20 +1695,34 @@ export default function TableManagementPage() {
                 </div>
               ) : (
                 <Tabs defaultValue="columns" className="flex min-h-0 flex-1 flex-col">
-                  <TabsList className="h-8 w-fit shrink-0 self-start mx-4 mt-1">
-                    <TabsTrigger value="columns" className="flex items-center gap-1.5 text-xs">
-                      <Columns3 className="h-3.5 w-3.5" />
+                  <TabsList className="h-auto w-full shrink-0 justify-start gap-1 rounded-none border-b bg-transparent p-0">
+                    <TabsTrigger
+                      value="columns"
+                      className={cn(
+                        "flex items-center gap-2 rounded-none border-b-2 border-transparent bg-transparent px-4 py-2.5 text-sm font-medium text-muted-foreground transition-colors",
+                        "hover:text-foreground",
+                        "data-[state=active]:border-primary data-[state=active]:bg-transparent data-[state=active]:text-primary data-[state=active]:shadow-none",
+                      )}
+                    >
+                      <Columns3 className="h-4 w-4" />
                       컬럼
                     </TabsTrigger>
-                    <TabsTrigger value="references" className="flex items-center gap-1.5 text-xs">
-                      <Link2 className="h-3.5 w-3.5" />
+                    <TabsTrigger
+                      value="references"
+                      className={cn(
+                        "flex items-center gap-2 rounded-none border-b-2 border-transparent bg-transparent px-4 py-2.5 text-sm font-medium text-muted-foreground transition-colors",
+                        "hover:text-foreground",
+                        "data-[state=active]:border-primary data-[state=active]:bg-transparent data-[state=active]:text-primary data-[state=active]:shadow-none",
+                      )}
+                    >
+                      <Link2 className="h-4 w-4" />
                       참조
                       {(() => {
                         const refCount = columns.filter((c) =>
                           ["entity", "code", "category", "numbering"].includes(c.input_type),
                         ).length;
                         return refCount > 0 ? (
-                          <Badge variant="secondary" className="ml-1 h-4 px-1.5 text-[10px]">
+                          <Badge variant="secondary" className="ml-1.5 h-5 px-1.5 text-[11px]">
                             {refCount}
                           </Badge>
                         ) : null;