refactor: remove translation feature

Remove the translation feature including:
- Translation services (Smesh API and LibreTranslate)
- TranslationServiceProvider and context
- TranslateButton component
- Translation settings page
- useTranslatedEvent hook
- Translation-related types and i18n strings

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/types/index.d.ts

@@ -142,22 +142,6 @@ export type TEmoji = {
   url: string
 }
 
-export type TTranslationAccount = {
-  pubkey: string
-  api_key: string
-  balance: number
-}
-
-export type TTranslationServiceConfig =
-  | {
-      service: 'smesh'
-    }
-  | {
-      service: 'libre_translate'
-      server?: string
-      api_key?: string
-    }
-
 export type TMediaUploadServiceConfig =
   | {
       type: 'nip96'