fix(frontend): login P0 — 去卡头重复、offline 文案、显密可键盘

去掉卡内盾牌标题；后端不可用改为「服务暂不可用」并禁用登录钮；显密切换可 Tab 聚焦。

frontend/src/i18n/locales/en/common.ts

@@ -11,6 +11,7 @@ export default {
     collectors: 'Log Collectors',
     logs: 'Log Query',
     alerts: 'Alerts',
+    analysis: 'Log Analysis',
     settings: 'Settings',
     users: 'Users',
     login: 'Sign In',
@@ -42,8 +43,10 @@ export default {
     errCredential: 'Invalid username or password',
     errConn: 'Cannot reach the backend. Make sure it is running on port 8080.',
     errFallback: 'Sign-in failed',
-    backendDown: 'Backend is not running',
-    backendDownHint: 'Cannot reach the API service. Start the backend first:',
+    backendDown: 'Service temporarily unavailable',
+    showPassword: 'Show password',
+    hidePassword: 'Hide password',
+    backendDownHint: 'Cannot reach the service. Try again later or contact an admin.',
   },
   dialog: {
     confirmTitle: 'Confirm Deletion',
@@ -92,6 +95,17 @@ export default {
   spinner: {
     default: 'Loading...',
   },
+  range: {
+    lastMinutes: 'Last {{count}} minutes',
+    lastHours: 'Last {{count}} hours',
+    lastHours_one: 'Last {{count}} hour',
+    custom: 'Custom time',
+    title: 'Select time range',
+    start: 'Start time',
+    end: 'End time',
+    apply: 'Apply',
+    recent: 'Recently used',
+  },
   password: {
     hide: 'Hide password',
     show: 'Show password',