Synchronize translations with sources

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• synchronize lang_en.json with extracted source translation keys
• update all locale files to 100% computed translation coverage
• prune stale locale-only keys and normalize locale key ordering
• update translation percentage metadata
• treat universal non-translatable values such as MSI, MSIX, placeholder-only format strings, and your@email.com as intentional source-equal entries in translation status

Validation

• pwsh .\scripts\translation\Verify-Translations.ps1
• pwsh .\.agents\skills\translation-source-sync\scripts\sync-translation-sources.ps1 -CheckOnly
• translation status JSON check: 58 non-English languages, 0 incomplete rows