fix: 분류 소분류 영역 배경색 구분 — 회색 박스로 대분류와 시각적 분리

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/views/account/AccountView.vue

@@ -1,4 +1,4 @@
-<script setup>
+1<script setup>
 import { computed, nextTick, onMounted, reactive, ref, watch } from 'vue'
 import { accountApi } from '@/api/accountApi'
 import { reminders } from '@/native/reminders'
@@ -1913,8 +1913,9 @@ button.primary {
   gap: 0.35rem;
 }
 .acc-sub-grid {
-  padding-top: 0.15rem;
-  border-top: 1px solid var(--color-border);
+  padding: 0.4rem;
+  border-radius: 6px;
+  background: var(--color-background-soft);
 }
 .acc-chip {
   flex: 1 1 calc(25% - 0.35rem);
@@ -1938,7 +1939,7 @@ button.primary {
   font-weight: 600;
 }
 .acc-chip.sub {
-  background: var(--color-background-soft);
+  background: var(--color-background);
 }
 .acc-chip.sub.active {
   border-color: hsla(160, 100%, 37%, 1);