feat: localize default strategy names by UI language at registration

- Pass `lang` from register request body to createDefaultStrategies
- Support zh/en/id locales for strategy names and descriptions
- Wrap strategy creation in a transaction to prevent partial writes
- Frontend sends current UI language in register request body
- Strategy list UI: 2-line clamp, unselected border, larger spacing, smaller font for non-zh

web/src/contexts/AuthContext.tsx

@@ -3,6 +3,7 @@ import { flushSync } from 'react-dom'
 import { getSystemConfig } from '../lib/config'
 import { reset401Flag, httpClient } from '../lib/httpClient'
 import { getPostAuthPath, setUserMode, type UserMode } from '../lib/onboarding'
+import { useLanguage } from './LanguageContext'
 
 interface User {
   id: string
@@ -41,6 +42,7 @@ interface AuthContextType {
 const AuthContext = createContext<AuthContextType | undefined>(undefined)
 
 export function AuthProvider({ children }: { children: React.ReactNode }) {
+  const { language } = useLanguage()
   const [user, setUser] = useState<User | null>(null)
   const [token, setToken] = useState<string | null>(null)
   const [isLoading, setIsLoading] = useState(true)
@@ -208,7 +210,8 @@ export function AuthProvider({ children }: { children: React.ReactNode }) {
       email: string
       password: string
       beta_code?: string
-    } = { email, password }
+      lang?: string
+    } = { email, password, lang: language }
     if (betaCode) {
       requestBody.beta_code = betaCode
     }