🐛 fix(config-secret-storage): 修复密文编辑与状态残留问题

- 修复自定义连接编辑时已保存 DSN 无法留空沿用的问题
- 重置 AI 供应商编辑态与清空密钥开关，避免关闭后状态残留
- 对齐浏览器 mock 复制连接的 config.id 语义并补充回归测试

frontend/src/utils/browserMockConnections.ts

@@ -0,0 +1,47 @@
+export const cloneBrowserMockValue = <T,>(value: T): T => {
+  try {
+    return JSON.parse(JSON.stringify(value));
+  } catch {
+    return value;
+  }
+};
+
+export const resolveBrowserMockSecretFlag = (nextValue: unknown, clearFlag: boolean, existingFlag?: boolean) => {
+  if (String(nextValue ?? '') !== '') return true;
+  if (clearFlag) return false;
+  return !!existingFlag;
+};
+
+export const buildBrowserMockDuplicateName = (rawName: string, items: any[]): string => {
+  const baseName = String(rawName || '').trim() || '连接';
+  const suffix = ' - 副本';
+  const usedNames = new Set(items.map((item) => String(item?.name || '').trim()));
+  let candidate = `${baseName}${suffix}`;
+  let counter = 2;
+  while (usedNames.has(candidate)) {
+    candidate = `${baseName}${suffix} ${counter}`;
+    counter += 1;
+  }
+  return candidate;
+};
+
+interface DuplicateBrowserMockConnectionInput {
+  existing: any;
+  items: any[];
+  nextId: string;
+}
+
+export const duplicateBrowserMockConnection = ({ existing, items, nextId }: DuplicateBrowserMockConnectionInput) => {
+  const duplicated = cloneBrowserMockValue({
+    ...existing,
+    id: nextId,
+    name: buildBrowserMockDuplicateName(existing?.name, items),
+    config: {
+      ...cloneBrowserMockValue(existing?.config),
+      id: nextId,
+    },
+    includeDatabases: Array.isArray(existing?.includeDatabases) ? [...existing.includeDatabases] : undefined,
+    includeRedisDatabases: Array.isArray(existing?.includeRedisDatabases) ? [...existing.includeRedisDatabases] : undefined,
+  });
+  return duplicated;
+};