fix: 바텀 내비게이션 라벨 가독성 개선

- 라벨 0.68→0.8rem·굵기 500·불투명도 0.92, 아이콘 22→25px, 바 높이 56→62px
- 텍스트가 너무 작아 메뉴 구분이 안 되던 문제 해소

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/layout/AppBottomNav.vue

@@ -74,7 +74,7 @@ function goSettings() {
   display: flex;
   align-items: stretch;
   justify-content: space-around;
-  height: 56px;
+  height: 62px;
   padding-bottom: env(safe-area-inset-bottom, 0);
   background: var(--color-background-soft);
   border-top: 1px solid var(--color-border);
@@ -85,18 +85,22 @@ function goSettings() {
   flex-direction: column;
   align-items: center;
   justify-content: center;
-  gap: 0.15rem;
+  gap: 0.25rem;
   border: 0;
   background: transparent;
   color: var(--color-text);
   cursor: pointer;
-  font-size: 0.68rem;
+  font-size: 0.8rem;
-  opacity: 0.78;
+  font-weight: 500;
+  opacity: 0.92;
   transition: opacity 0.15s ease, color 0.15s ease;
 }
+.nav-btn span {
+  line-height: 1;
+}
 .nav-btn svg {
-  width: 22px;
+  width: 25px;
-  height: 22px;
+  height: 25px;
 }
 .nav-btn:hover {
   opacity: 1;