feat(account): 按代理地址去重、默认账户名、前端重复提示与 DB 唯一约束

后端:
- 导入去重改为按 proxy_address（existsByProxyAddress），重复时返回 ACCOUNT_ALREADY_EXISTS(4601)
- 未填账户名时默认生成 SAFE/MAGIC-代理地址后4位（无中括号）
- Controller 识别 ACCOUNT_ALREADY_EXISTS 并返回对应错误码

前端:
- 导入失败时 message.error 提示；code=4601 时使用 accountImport.duplicateAccount 多语言
- store 抛出错误时附带 response.data.code 供表单判断

数据库 V33:
- 移除 wallet_address 唯一约束，新增 proxy_address 唯一约束
- 已存在账户的 wallet_type 统一更新为 safe

实体:
- Account.walletAddress 取消 unique，Account.proxyAddress 设为 unique

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/main/resources/db/migration/V33__unique_constraint_proxy_address_instead_of_wallet.sql

@@ -0,0 +1,38 @@
+-- ============================================
+-- V33: 唯一约束从 wallet_address 改为 proxy_address
+-- 允许同一 EOA 以不同代理类型（Magic/Safe）各导入一个账户，按代理地址去重
+-- ============================================
+
+-- 将已存在账户的 wallet_type 统一为 safe（历史数据兼容）
+UPDATE wallet_accounts SET wallet_type = 'safe';
+
+-- 删除 wallet_address 上的唯一约束（通过 KEY_COLUMN_USAGE 定位到该列的约束名）
+SET @uk_name = (SELECT kcu.CONSTRAINT_NAME
+                FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu
+                JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
+                  ON kcu.TABLE_SCHEMA = tc.TABLE_SCHEMA AND kcu.TABLE_NAME = tc.TABLE_NAME AND kcu.CONSTRAINT_NAME = tc.CONSTRAINT_NAME
+                WHERE kcu.TABLE_SCHEMA = DATABASE()
+                AND kcu.TABLE_NAME = 'wallet_accounts'
+                AND tc.CONSTRAINT_TYPE = 'UNIQUE'
+                AND kcu.COLUMN_NAME = 'wallet_address'
+                LIMIT 1);
+SET @sql = IF(@uk_name IS NOT NULL,
+              CONCAT('ALTER TABLE wallet_accounts DROP INDEX ', @uk_name),
+              'SELECT 1');
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- 为 proxy_address 添加唯一约束（若已存在则跳过）
+SET @uk_exists = (SELECT 1 FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
+                  WHERE TABLE_SCHEMA = DATABASE()
+                  AND TABLE_NAME = 'wallet_accounts'
+                  AND CONSTRAINT_TYPE = 'UNIQUE'
+                  AND CONSTRAINT_NAME = 'uk_wallet_accounts_proxy_address'
+                  LIMIT 1);
+SET @sql2 = IF(@uk_exists IS NULL,
+               'ALTER TABLE wallet_accounts ADD UNIQUE KEY uk_wallet_accounts_proxy_address (proxy_address)',
+               'SELECT 1');
+PREPARE stmt2 FROM @sql2;
+EXECUTE stmt2;
+DEALLOCATE PREPARE stmt2;