Add Ukrainian localization - #719

Summary

Adds Ukrainian (uk) localization to Clipy.

• Translates the app menu, alerts, settings window, every settings panel, and the snippets editor.
• Uses сніпет consistently in the Ukrainian interface.
• Replaces the Japanese toolbar font with the macOS system font so Cyrillic labels render at their normal width.
• Labels the shortcut section as Комбінація клавіш and enlarges its editor label to avoid clipping.

Validation

• Built successfully with Xcode 26.6 using ad-hoc signing.
• Compiled all localized nibs with ibtool.
• Checked all .strings resources and the project file with plutil.
• Launched the Ukrainian build manually and reviewed the updated settings and snippets editor labels.

Notes

The local full test run has pre-existing environment-related failures: hotkey tests expect Latin key symbols while the Ukrainian keyboard layout produces Cyrillic symbols. The OCR test suite passed when rerun.