feat: Add Polish (PL) language support

[Levyblack]

Description

This pull request introduces full Polish (PL) language support.
I have created the pl.ts file within src/assets/locales/ following the
existing i18n structure. All core features, wallet settings, and
transactional labels have been translated to provide a native experience
for Polish users.-->

Related Issue

This is a community-driven feature request to expand the wallet's
accessibility. No specific issue was open, but adding Polish support
is a valuable improvement for the growing XVG community in Poland.

Motivation and Context

The goal is to make MyVergies more accessible to non-English speakers
in the Polish region. Providing a native interface reduces entry
barriers for new users and strengthens the Verge ecosystem worldwide.. -->

How Has This Been Tested?

Verified the pl.ts file for syntax errors.

• Matched all keys against the base en.ts file to ensure 100% coverage.
• Confirmed that the automatic locale loader in locales.ts correctly
  detects the new file via regex. -->

Screenshots (if appropriate):

Types of changes

Types of changes (Rodzaje zmian)
[ ] Bug fix

[x] New feature

[ ] Breaking change

Checklist (Lista kontrolna)

[x] My code follows the code style of this project.

[ ] My change requires a change to the documentation.

[ ] I have updated the documentation accordingly.