fix(i18n): localize 1.5.9 UI gaps

[VailElla]

Description

This PR is a reviewed replacement for #1360, based on the current upstream main. It closes a scoped set of user-visible 1.5.9 localization gaps while preserving canonical filename tokens and the current Simplified Chinese terminology, including 克隆. Unrelated local JXL, RAW, and performance changes are excluded.

Type of Change

• Bug fix
• New feature
• Breaking change
• Performance improvement
• Code refactoring
• Documentation update
• UI/UX improvement
• Build/CI or Dependency update

Changes Made

• Localize metadata field labels and supported enum values, including non-RAW DateTime, DateTimeDigitized, and white-balance aliases.
• Localize built-in tags, import file dialogs, filename-variable display labels, sidecar UI, unknown TIFF tags, and macOS bundle localizations.
• Keep canonical filename tokens such as {original_filename} unchanged while translating their visible labels.
• Include the shipped Korean locale in the i18next CLI configuration.
• Preserve the current Simplified Chinese 克隆 terminology instead of the older wording used by fix(i18n): fill Chinese gaps in metadata and dialogs #1360.
• The extended-EXIF additions are complete for English and Chinese. Other shipped locales retain the existing English fallback for these new keys; a full translation sweep is deliberately out of scope.

Screenshots/Videos

Testing

• I have tested these changes locally and confirmed that they work as expected without issues

• npm run build — passed; only the existing large-chunk warning remains

• plutil -lint src-tauri/Info.plist — passed

• Locale JSON parsing — passed

• Changed-file Prettier check — passed

• git diff --check origin/main...HEAD — passed

• npm run typecheck and npm run i18n:check still report existing repository-wide findings; no new diagnostics were isolated to the touched code or newly added locale entries.

Test Configuration:

• OS: macOS 26.5.2
• Hardware: Apple M4 Pro (arm64)

Checklist

• My code follows the project's code style
• I haven't added unnecessary AI-generated code comments
• My changes generate no new warnings or errors

Additional Notes

#1360 has been closed as superseded by this replacement PR. The editable filename template intentionally keeps canonical tokens such as {original_filename} so cross-language presets and clipboard content remain portable. The original local worktree changes remain separate and were not included here.

AI Disclaimer:

Please state the involvement of AI in this PR:

• This PR is entirely AI-generated
• This PR is AI-generated but guided by a human
• This PR was handwritten with AI assistance (spell check, logic suggestions, error resolving)
• This PR contains only blood, sweat, and coffee (AI-free)