Add more interface languages

[lippdev]

The UI strings live in src/ConsoleMode/Resources/Strings.<culture>.json (pt-BR and en-US today). Missing keys fall back to Portuguese.

To add a language (e.g. es-ES):

1. Copy Strings.en-US.json to Strings.es-ES.json and translate the values (keep the keys)
2. Add an <EmbeddedResource> line for it in ConsoleMode.csproj, next to the existing two
3. In Services/LocalizationService.cs: add a constant, load it into Catalogs, and update SetLanguage/Normalize, which currently only know pt-BR and en-US
4. Add it to LanguageOptions in ViewModels/MainViewModel.cs (plus a LanguageXxx label in each strings file)
5. Optional: Services/ReleaseNotes.cs picks English or Portuguese notes; a new language can use English

Spanish, French and German would be great first additions.

[lippdev]

Spanish (es-ES) is in, and the steps above got shorter. To add a language now:

1. Copy src/ConsoleMode/Resources/Strings.en-US.json to Strings.<code>.json and translate the values (keep the keys; the tests fail if any key is missing).
2. Add an <EmbeddedResource> line for it in src/ConsoleMode/ConsoleMode.csproj and in tests/ConsoleMode.Tests/ConsoleMode.Tests.csproj, next to the existing ones.
3. Add one entry to SupportedLanguages in Services/LocalizationService.cs (code + the language's own name). The picker, the Windows-language detection and the fallbacks come from that list.
4. Optional, for the installer: a [Languages] line, the three CustomMessages and a Language registry line in build/ConsoleMode.iss.

Release notes stay in Portuguese and English; other languages read the English section of the update notice. Translations welcome, one PR per language.