Add localization

[nikaose]

• Implemented i18n.js module for handling language loading and translations in the application.
• Created en.json for English translations including UI elements, tooltips, crops, and wiki links.
• Created ru.json for Russian translations with similar structure and content.

[Thorinair]

This looks simple enough. How does it behave in case something is not translated, like when adding new text lines? Does it just default to en?

[nikaose]

This looks simple enough. How does it behave in case something is not translated, like when adding new text lines? Does it just default to en?

Right now the app defaults to English on init.
For missing keys in a non-English locale, it does not currently fall back to enper key - returns the key itself (e.g. ui.new_label), so missing translations are visible immediately. If you prefer, I can add a per-key English fallback
I'll also add that localization support is currently missing for the Change Log page, Help page, and, for example, for products with the jarType, kegType, dehydratorType, etc.

[nikaose]

You can see the localization in action on the demo page: https://nikaose.github.io/Stardew-Profits/