fix(web): capitalize localized language names

[dibenkobit]

What changed

Language labels now start with an uppercase letter across tables, selectors, language/model pages, releases, and the run builder. Shared formatting also covers native names and preserves unknown language tags.

Why

Intl.DisplayNames returns lowercase Russian names, causing inconsistent presentation next to English labels.

Verification

• Passed pnpm format:check, pnpm lint, pnpm --filter @llang-gap/web typecheck, and pnpm --filter @llang-gap/web build.
• Passed focused language-label, language-catalog, and leaderboard-column tests: 24 tests.
• Browser checked /en/languages/ru and /ru/languages/ru at 1440×1000; inspected matching screenshots before and after.

UI changes

Checklist

• This PR addresses one concern, and I reviewed the diff.
• I explained the problem, the change, and the verification results.
• I updated affected documentation and regression coverage, where applicable.
• I attached UI evidence and checked the required language(s), where applicable.

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Project	Deployment	Actions	Updated
langgap-web	Ready	Preview	Sep 9, 2026 12:15am UTC