백품타 랭킹 화면 필터 칩/내 순위 강조색을 테마 강조색으로 변경

학년/기간 필터 칩(ChoiceChip)의 selectedColor와 "내 순위" 행 강조 배경이
AppPalette.ink로 고정돼 있어서 테마를 적용해도 검정으로 남아있었다.
globalProfileTheme의 accent를 쓰도록 변경.

lib/ui/study_ranking_screen.dart

@@ -3,6 +3,7 @@
 import 'package:flutter/material.dart';
 import '../function/study_ranking_controller.dart';
 import '../theme/app_palette.dart';
+import '../theme/theme_sync.dart';
 import 'title_pill.dart';
 
 class StudyRankingScreen extends StatefulWidget {
@@ -126,6 +127,9 @@ class _StudyRankingScreenState extends State<StudyRankingScreen> {
                                   r['studentId'] == widget.myStudentId;
                               final int rank = (r['rank'] as num).toInt();
                               final medalColor = _rankColor(rank);
+                              final accentColor =
+                                  globalProfileTheme.value?.accent ??
+                                  AppPalette.ink;
 
                               return Container(
                                 margin: const EdgeInsets.only(bottom: 8),
@@ -134,14 +138,10 @@ class _StudyRankingScreenState extends State<StudyRankingScreen> {
                                   vertical: 12,
                                 ),
                                 decoration: BoxDecoration(
-                                  color: isMe
-                                      ? AppPalette.ink
-                                      : AppPalette.paper,
+                                  color: isMe ? accentColor : AppPalette.paper,
                                   borderRadius: BorderRadius.circular(14),
                                   border: Border.all(
-                                    color: isMe
-                                        ? AppPalette.ink
-                                        : AppPalette.sage,
+                                    color: isMe ? accentColor : AppPalette.sage,
                                   ),
                                 ),
                                 child: Row(
@@ -206,14 +206,15 @@ class _StudyRankingScreenState extends State<StudyRankingScreen> {
 
   Widget _periodChip(String value, String label) {
     final bool selected = _controller.period == value;
+    final accentColor = globalProfileTheme.value?.accent ?? AppPalette.ink;
     return Expanded(
       child: ChoiceChip(
         label: Center(child: Text(label)),
         selected: selected,
         onSelected: (_) => _controller.setPeriod(value),
-        selectedColor: AppPalette.ink,
+        selectedColor: accentColor,
         labelStyle: TextStyle(
-          color: selected ? Colors.white : AppPalette.ink,
+          color: selected ? Colors.white : accentColor,
           fontWeight: FontWeight.bold,
         ),
       ),
@@ -222,12 +223,13 @@ class _StudyRankingScreenState extends State<StudyRankingScreen> {
 
   Widget _scopeChip(String value, String label) {
     final bool selected = _controller.scope == value;
+    final accentColor = globalProfileTheme.value?.accent ?? AppPalette.ink;
     return Expanded(
       child: ChoiceChip(
         label: Center(child: Text(label, style: const TextStyle(fontSize: 13))),
         selected: selected,
         onSelected: (_) => _controller.setScope(value),
-        selectedColor: AppPalette.ink,
+        selectedColor: accentColor,
         backgroundColor: AppPalette.mist,
         labelStyle: TextStyle(
           color: selected ? Colors.white : Colors.grey[600],