feat(account): 가계부 데이터 전체 삭제 API (DELETE /account/all)

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

src/main/java/com/sb/web/account/controller/BackupController.java

@@ -30,4 +30,11 @@ public class BackupController {
         backupService.restore(current.getId(), req);
         return ResponseEntity.noContent().build();
     }
+
+    @DeleteMapping("/all")
+    public ResponseEntity<Void> deleteAll(
+            @RequestAttribute(AuthInterceptor.CURRENT_MEMBER) SessionUser current) {
+        backupService.deleteAll(current.getId());
+        return ResponseEntity.noContent().build();
+    }
 }

src/main/java/com/sb/web/account/service/BackupService.java

@@ -38,6 +38,22 @@ public class BackupService {
     private final BudgetService budgetService;
     private final QuickEntryService quickEntryService;
 
+    @Transactional
+    public void deleteAll(Long memberId) {
+        backupMapper.deleteEntryTags(memberId);
+        backupMapper.deleteEntries(memberId);
+        backupMapper.deleteRecurrings(memberId);
+        backupMapper.deleteBudgets(memberId);
+        backupMapper.deleteBudgetIncome(memberId);
+        backupMapper.deleteQuickEntries(memberId);
+        backupMapper.deleteInvestTrades(memberId);
+        backupMapper.deleteInvestHoldings(memberId);
+        backupMapper.deleteCategories(memberId);
+        backupMapper.deleteTags(memberId);
+        backupMapper.deleteWallets(memberId);
+        log.info("[deleteAll] member={} — all account data deleted", memberId);
+    }
+
     @Transactional
     public void restore(Long memberId, RestoreRequest req) {
         if (isEmpty(req)) {