Add Brazilian Portuguese (pt-BR) localization

[ericklucioh]

Summary

• Add Brazilian Portuguese (pt-BR) localization.
• Translate vtm menus, tooltips, status messages, keyboard modes, and interface labels.
• Preserve English (en-US) as the fallback language.
• Preserve existing placeholders, ANSI escape sequences, field names, and configuration structure.

This implements the contribution proposed in #960.

Validation

• Confirmed that pt-BR contains the same 123 localization fields as en-US.
• Verified that placeholders and configuration references are preserved.
• Ran git diff --check.
• Kept the change limited to src/vtm.xml.

Closes #960

[o-sdn-o]

The tooltip formatting is a bit off. In vtm, it's done using spaces. You need to add spaces to create a neat tooltip rectangle.

[o-sdn-o]

The formatting here is a bit off:

[ericklucioh]

Hello.

I fixed the spaces

[o-sdn-o]

It will compile now, I'll take a look.

[o-sdn-o]

I'll merge it as is, but then I'll polish it up a bit; there are some bugs there (but you can fix them yourself if you want). I really need to automate tooltip formatting (formatting with spaces is a relic of the past here).

[o-sdn-o]

Great! Let's merge this PR. Thank you so much!