feat(i18n): Add GitHub Action for automated translations (WP07)

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: P2 (Nice to have for v1.2.0) Work Package: WP07

Goal

Automated translation workflow that triggers on English content changes and creates PRs with GPT-4 translations for all 14 non-English locales.

Acceptance Criteria

• Update locales/en/navigation.json, push to main
• GitHub Action runs successfully
• Creates PR with translations within 1 hour
• PR includes translations for all 14 locales with preserved placeholders

Subtasks

• T028: Create .github/workflows/translate.yml workflow file
• T029: Create .github/scripts/translate.js Node.js translation script
• T030: Configure OpenAI API integration (official Node.js SDK)
• T031: Add matrix strategy for 14 locales with max-parallel: 3
• T032: Add translation cache using actions/cache@v5
• T033: Add PR creation using peter-evans/create-pull-request@v6
• T034: Test workflow with sample English content change

Implementation Notes

1. Use official OpenAI Node.js SDK
2. Translation script should:
   • Read changed English JSON files from git diff
   • For each file/locale: call GPT-4 with context-aware prompt
   • Preserve placeholders, brand names, technical terms
   • Handle rate limiting with retries and exponential backoff
3. Contract available at: kitty-specs/004-add-internationalization-i18n/contracts/github-action-workflow.yml

Files to Create/Modify

• .github/workflows/translate.yml (new)
• .github/scripts/translate.js (new)

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