Feature: Add Simplified Chinese (zh-CN) Localization & Dynamic UI Language Switching

[yuruichang]

Hi there! Thanks for this amazing tool!

I have implemented a complete multi-language framework for SMT and added the Simplified Chinese (zh-CN) localization.

Here is a summary of the changes:

1. Dynamic UI Switching: Refactored hard-coded UI strings (like menus, datagrid headers, and AvalonDock tabs) to use DynamicResource.
2. Resource Dictionaries: Added Languages/en-US.xaml and Languages/zh-CN.xaml for seamless UI language swapping without restarting the app.
3. Map & Data Localization: Updated the drawing logic in RegionControl and RegionsViewControl to use the .LocalizedName property. Fallback to English is guaranteed if the Chinese translation is missing.
4. PropertyGrid Bilingual: Modified the [Category] and [DisplayName] in MapColours.cs to a "English / 中文" bilingual format, as Xceed PropertyGrid metadata cannot be dynamically swapped at runtime.
5. Preferences: Added a language selection ComboBox in the Settings window. The app will default to en-US on the first launch, and will remember the user's choice seamlessly.

All core functionalities and the default en-US experience remain intact and completely unaffected.

Hope this helps more Chinese EVE players enjoy SMT! Let me know if any further adjustments are needed.