feat(flutter): 优化登录页与底部导航

lib/l10n/app_en.arb

@@ -253,6 +253,7 @@
   "authSignInTitle": "Welcome back",
   "authSignUpTitle": "Create your account",
   "authSubtitle": "Sign in with your email and password.",
+  "authBrandTagline": "Short dramas made for Indonesia",
   "authEmailLabel": "Email",
   "authPasswordLabel": "Password",
   "authPasswordHint": "At least 8 characters, letters and numbers",
@@ -267,6 +268,8 @@
   "authGateTitle": "Sign in to continue",
   "authGateMessage": "Watch history, favorites, comments and downloads need an account.",
   "authGateAction": "Sign In",
+  "showPassword": "Show password",
+  "hidePassword": "Hide password",
   "cancel": "Not now",
   "noEpisodesYet": "No playable episodes yet.",
   "networkError": "Network is unreachable. Please check your connection and retry.",