fix(dashboard): update password hints to reference CLI instead of "default password"

Security improvement: password is now set via `astrbot conf admin` CLI
command rather than being a hardcoded default. Updated all relevant
i18n strings to reflect this change.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dashboard/src/i18n/locales/en-US/core/header.json

@@ -81,7 +81,7 @@
   },
   "accountDialog": {
     "title": "Modify Account",
-    "securityWarning": "Security Reminder: Please change the default password to ensure account security",
+    "securityWarning": "Security Reminder: Use `astrbot conf admin` to change your password for account security",
     "form": {
       "currentPassword": "Current Password",
       "newPassword": "New Password",
@@ -90,7 +90,7 @@
       "passwordHint": "Password must be at least 8 characters",
       "confirmPasswordHint": "Please enter new password again to confirm",
       "usernameHint": "Leave blank to keep current username",
-      "defaultCredentials": "Default username and password are both astrbot"
+      "defaultCredentials": "Default username: astrbot. Use `astrbot conf admin` to set your password"
     },
     "validation": {
       "passwordRequired": "Please enter password",

dashboard/src/i18n/locales/zh-CN/core/header.json

@@ -81,7 +81,7 @@
   },
   "accountDialog": {
     "title": "修改账户",
-    "securityWarning": "安全提醒: 请修改默认密码以确保账户安全",
+    "securityWarning": "安全提醒: 请通过 `astrbot conf admin` 命令修改密码以确保账户安全",
     "form": {
       "currentPassword": "当前密码",
       "newPassword": "新密码",
@@ -90,7 +90,7 @@
       "passwordHint": "密码长度至少 8 位",
       "confirmPasswordHint": "请再次输入新密码以确认",
       "usernameHint": "留空表示不修改用户名",
-      "defaultCredentials": "默认用户名和密码均为 astrbot"
+      "defaultCredentials": "初始用户名：astrbot，请使用 `astrbot conf admin` 设置密码"
     },
     "validation": {
       "passwordRequired": "请输入密码",