feat(frontend): 支持批量编辑和管理已保存登录凭证

为连接表单补充已保存登录凭证的校验与提交流程，
允许新增、批量新增、测试连接时优先使用凭证

在连接列表中新增登录凭证管理入口，并支持批量编辑
时按连接类型筛选和应用已保存凭证

补充中英日文案，并修复 SSH 密钥选择器的绑定兼容性

packages/frontend/src/locales/en-US.json

@@ -215,6 +215,8 @@
       "title": "Batch Edit Connections",
       "editSelected": "Edit Selected",
       "noChange":"No change",
+      "savedCredentialMixedType": "Select only one connection type before applying a saved credential in batch.",
+      "savedCredentialTypeHint": "Batch apply works only for the same connection type",
       "selectedItems":"{count} items selected",
       "deleteSelectedButton": "Delete Selected",
       "deleteSelectedTooltip": "Delete selected connections",
@@ -273,6 +275,23 @@
       "connectionModeProxy": "Proxy Server",
       "connectionModeJumpHost": "Jump Host",
       "connectionType": "Connection Type:",
+      "credentialSource": "Credential Source",
+      "credentialSourceDirect": "Account / Password / Key",
+      "credentialSourceSaved": "Use Saved Credential",
+      "savedLoginCredential": "Login Credential",
+      "selectLoginCredential": "Select a saved credential",
+      "manageLoginCredentials": "Manage Login Credentials",
+      "savedCredentialHint": "Saved credentials take priority during test and connect. You can switch back to direct input anytime.",
+      "loginCredentialManager": "Login Credentials",
+      "addLoginCredential": "Add Login Credential",
+      "editLoginCredential": "Edit Login Credential",
+      "noLoginCredentials": "No saved login credentials yet",
+      "clearSavedCredential": "Clear saved credential",
+      "errorLoginCredentialRequired": "Please select a saved login credential.",
+      "errorCredentialRequiredFields": "Name and username are required.",
+      "errorCredentialDetails": "Failed to load login credential details.",
+      "confirmDeleteCredential": "Delete login credential {name}?",
+      "errorDeleteCredential": "Failed to delete login credential.",
       "typeSsh": "SSH",
       "typeRdp": "RDP",
       "typeVnc": "VNC",

packages/frontend/src/locales/ja-JP.json

@@ -213,6 +213,23 @@
             "errorPasswordRequiredForBatchSSH": "SSH (パスワード認証) 接続を一括追加する場合、パスワードを提供する必要があります。",
             "errorPasswordRequiredForBatchRDP": "RDP接続を一括追加する場合、パスワードを提供する必要があります。",
             "errorPasswordRequiredForBatchVNC": "VNC接続を一括追加する場合、VNCパスワードを提供する必要があります。",
+            "credentialSource": "認証ソース",
+            "credentialSourceDirect": "アカウント / パスワード / キー",
+            "credentialSourceSaved": "保存済み認証情報を使用",
+            "savedLoginCredential": "ログイン認証情報",
+            "selectLoginCredential": "ログイン認証情報を選択してください",
+            "manageLoginCredentials": "ログイン認証情報を管理",
+            "savedCredentialHint": "保存済み認証情報はテストと接続時に優先して使用されます。いつでも直接入力へ戻せます。",
+            "loginCredentialManager": "ログイン認証情報",
+            "addLoginCredential": "ログイン認証情報を追加",
+            "editLoginCredential": "ログイン認証情報を編集",
+            "noLoginCredentials": "保存済みのログイン認証情報はありません",
+            "clearSavedCredential": "保存済み認証情報を解除",
+            "errorLoginCredentialRequired": "保存済みのログイン認証情報を選択してください。",
+            "errorCredentialRequiredFields": "名前とユーザー名は必須です。",
+            "errorCredentialDetails": "ログイン認証情報の詳細取得に失敗しました。",
+            "confirmDeleteCredential": "ログイン認証情報 {name} を削除しますか？",
+            "errorDeleteCredential": "ログイン認証情報の削除に失敗しました。",
             "errorBatchAddResult": "一括追加: {successCount} 件成功, {errorCount} 件失敗。最初のエラー: {firstErrorEncountered}",
             "successBatchAddResult": "一括追加成功: {successCount} 件の接続が作成されました。",
             "errorIpRangeNotAllowedInEditMode": "編集モードではIP範囲はサポートされていません。単一のIPアドレスを使用してください。",

packages/frontend/src/locales/zh-CN.json

@@ -217,6 +217,8 @@
       "title": "批量编辑连接",
       "selectedItems": "已选项目",
       "noChange": "保持不变",
+      "savedCredentialMixedType": "批量应用已保存凭证前，请先只选择同一种连接类型。",
+      "savedCredentialTypeHint": "仅支持同类型连接批量应用",
       "deleteSelectedButton": "删除选中",
       "deleteSelectedTooltip": "删除选中的连接",
       "confirmMessage": "您确定要删除选中的 {count} 个连接吗？此操作无法撤销。",
@@ -273,6 +275,23 @@
       "connectionModeProxy": "代理服务器",
       "connectionModeJumpHost": "跳板机",
       "connectionType": "连接类型",
+      "credentialSource": "认证来源",
+      "credentialSourceDirect": "账号密码 / 密钥",
+      "credentialSourceSaved": "使用已保存凭证",
+      "savedLoginCredential": "登录凭证",
+      "selectLoginCredential": "请选择登录凭证",
+      "manageLoginCredentials": "管理登录凭证",
+      "savedCredentialHint": "已保存凭证会在连接和测试时优先使用；切回直填后仍可继续手工输入。",
+      "loginCredentialManager": "登录凭证",
+      "addLoginCredential": "新增登录凭证",
+      "editLoginCredential": "编辑登录凭证",
+      "noLoginCredentials": "暂无登录凭证",
+      "clearSavedCredential": "取消已保存凭证",
+      "errorLoginCredentialRequired": "请选择已保存的登录凭证。",
+      "errorCredentialRequiredFields": "名称和用户名为必填项。",
+      "errorCredentialDetails": "获取登录凭证详情失败。",
+      "confirmDeleteCredential": "确认删除登录凭证 {name}？",
+      "errorDeleteCredential": "删除登录凭证失败。",
       "typeSsh": "SSH",
       "typeRdp": "RDP",
       "typeVnc": "VNC",