feat: 添加删除用户账户的接口，包含权限检查和自我删除限制

src/main/java/com/gameplatform/server/controller/admin/AccountController.java

@@ -76,6 +76,31 @@ public class AccountController {
         return accountService.resetPassword(id, req.getNewPassword(), Boolean.TRUE.equals(req.getForceLogout()));
     }
 
+    @DeleteMapping("/{id}")
+    @ResponseStatus(HttpStatus.NO_CONTENT)
+    @Operation(summary = "删除用户", description = "删除指定的用户账户，管理员不能删除自己或最后一个管理员")
+    public Mono<Void> delete(
+            @Parameter(description = "账户ID") @PathVariable Long id,
+            @Parameter(hidden = true) @RequestHeader("Authorization") String authHeader) {
+        return Mono.fromCallable(() -> {
+                    if (authHeader == null || !authHeader.startsWith("Bearer ")) {
+                        throw new IllegalArgumentException("Authorization header is required");
+                    }
+                    
+                    String token = authHeader.substring(7);
+                    io.jsonwebtoken.Claims claims = jwtService.parse(token);
+                    Long currentUserId = claims.get("userId", Long.class);
+                    
+                    if (currentUserId == null) {
+                        throw new IllegalArgumentException("Invalid token: userId not found");
+                    }
+                    
+                    return currentUserId;
+                })
+                .flatMap(currentUserId -> accountService.delete(id, currentUserId))
+                .then();
+    }
+
     @GetMapping("/me/points-balance")
     @Operation(summary = "获取当前用户积分余额", description = "根据token解析用户ID并获取当前用户的积分余额")
     public Mono<PointsBalanceResponse> getCurrentUserPointsBalance(