✨ feat(security): 完成配置密文存储前后端闭环

- 补齐连接与代理密文字段的保留替换清空语义

- 接通保存复制删除导入接口并返回 secretless 视图

- 刷新 Wails 绑定并补充实现留痕文档

frontend/src/utils/connectionSecretDraft.ts

@@ -0,0 +1,63 @@
+export interface ConnectionSecretDraftInput {
+  valueInput?: string;
+  hasSecret?: boolean;
+  clearSecret?: boolean;
+  forceClear?: boolean;
+  trimInput?: boolean;
+}
+
+export interface ConnectionSecretDraftResult {
+  value: string;
+  clearStoredSecret: boolean;
+  keepsStoredSecret: boolean;
+  hasSecretAfterSave: boolean;
+}
+
+export function resolveConnectionSecretDraft(input: ConnectionSecretDraftInput): ConnectionSecretDraftResult {
+  const rawValue = input.valueInput ?? '';
+  const value = input.trimInput ? String(rawValue).trim() : String(rawValue);
+
+  if (input.forceClear) {
+    return {
+      value: '',
+      clearStoredSecret: true,
+      keepsStoredSecret: false,
+      hasSecretAfterSave: false,
+    };
+  }
+
+  if (value !== '') {
+    return {
+      value,
+      clearStoredSecret: false,
+      keepsStoredSecret: false,
+      hasSecretAfterSave: true,
+    };
+  }
+
+  if (input.clearSecret) {
+    return {
+      value: '',
+      clearStoredSecret: true,
+      keepsStoredSecret: false,
+      hasSecretAfterSave: false,
+    };
+  }
+
+  if (input.hasSecret) {
+    return {
+      value: '',
+      clearStoredSecret: false,
+      keepsStoredSecret: true,
+      hasSecretAfterSave: true,
+    };
+  }
+
+  return {
+    value: '',
+    clearStoredSecret: false,
+    keepsStoredSecret: false,
+    hasSecretAfterSave: false,
+  };
+}
+