fix(i18n): complete Russian desktop fallback copy

[DrMaks22]

Summary

• route the Desktop intro/welcome copy through the existing i18n catalog, with Russian copy for the standard personality modes and safe English fallback for other locales
• fill the remaining visible Russian fallback gaps found during live Desktop QA: settings/sidebar/project actions, cron counters, context usage, preview save errors, assistant resume copy, and tool title templates
• polish Russian wording to avoid machine-translation artifacts while preserving command names, provider names, tool ids, paths, and technical tokens where appropriate

Verification

• npm run typecheck --workspace apps/desktop
• npm run test:ui --workspace apps/desktop -- src/i18n/languages.test.ts src/i18n/runtime.test.ts src/i18n/context.test.tsx src/components/language-switcher.test.tsx
• git diff --check -- apps/desktop/src/components/chat/intro.tsx apps/desktop/src/i18n/types.ts apps/desktop/src/i18n/index.ts apps/desktop/src/i18n/en.ts apps/desktop/src/i18n/ru.ts
• live smoke-tested in a separate local Hermes RU Test.app bundle on macOS; the main Hermes.app installation was not modified

This is intended as a follow-up polish patch for the canonical RU Desktop PR, so it should be easy to merge into NousResearch#46634 or cherry-pick if maintainers prefer another consolidation path.

[DrMaks22]

Follow-up pushed in 374e079 for the new screenshots showing remaining English in the RU desktop build.

Covered in this patch:

• routed the Mixture of Agents settings copy through the existing i18n catalog instead of hardcoded JSX strings;
• added RU copy for MoA preset/reference/aggregator controls;
• localized the stale auxiliary-model warning with proper Russian count handling;
• added RU platform onboarding copy for messaging integrations, including the Telegram intro that was falling back to English;
• added RU Telegram field copy for allow-all-users and home-channel/thread settings;
• updated the shared translation type plus EN/ZH keys so typecheck keeps all locales structurally complete.

Checks run on the patch branch:

• npm run typecheck --workspace apps/desktop
• npm run test:ui --workspace apps/desktop -- src/i18n/languages.test.ts src/i18n/runtime.test.ts src/i18n/context.test.tsx src/components/language-switcher.test.tsx
• git diff --check
• local Hermes RU Test.app pack/install smoke build

I also ran the ru-localization quality lint; its findings are in existing runtime YAML/docs surfaces, not in the changed desktop files.