feat(i18n): Add Language Switcher UI component (WP08)

Context

Part of the i18n feature implementation (branch: 004-add-internationalization-i18n).

Parent Work: Core i18n infrastructure complete in PR #383 + follow-up commits Priority: P3 (Nice to have for v1.2.0) Work Package: WP08 Depends On: #465 (WP07) can be done independently

Goal

Language selection UI component with localStorage persistence, performance optimization, and SEO enhancements.

Acceptance Criteria

• Language switcher appears in navigation with all 15 languages
• Selecting a language persists across sessions
• Page load time is within 100ms of English baseline
• Sitemap includes hreflang for SEO

Subtasks

• T035: Create website/src/components/LanguageSwitcher.astro with dropdown of all 15 languages
• T036: Add client-side localStorage persistence logic
• T037: Performance optimization - verify lazy loading of translations
• T038: Add hreflang sitemap to public/sitemap.xml for SEO

Implementation Notes

1. LanguageSwitcher component:

   • Display native language names (e.g., "Español", "日本語", "עברית")
   • Current language highlighted/selected
   • On change: redirect to corresponding locale URL
   • Use client-side script tag for interactivity

2. localStorage persistence:

   • Save as caroPreferredLanguage
   • On page load, check and redirect if different
   • Respect manual URL navigation

3. Performance:

   • Verify Astro's code splitting works
   • Measure with Lighthouse for baseline comparison

4. SEO:

   • Generate sitemap with all locale URLs
   • Include hreflang entries for each language version

Files to Create/Modify

• website/src/components/LanguageSwitcher.astro (new)
• website/src/components/Navigation.astro (add LanguageSwitcher)
• public/sitemap.xml or Astro sitemap config

Languages (15 total)

Code	Native Name	Direction
en	English	LTR
es	Español	LTR
fr	Français	LTR
pt	Português	LTR
de	Deutsch	LTR
ja	日本語	LTR
ko	한국어	LTR
ru	Русский	LTR
uk	Українська	LTR
he	עברית	RTL
ar	العربية	RTL
ur	اردو	RTL
hi	हिन्दी	LTR
fil	Filipino	LTR
id	Bahasa Indonesia	LTR

---

Deferred from i18n feature implementation. See kitty-specs/004-add-internationalization-i18n/tasks.md for full context.