Add Portuguese (pt-PT) translation

[huntsmarinho]

Description

Add complete European Portuguese (pt-PT) translation for the MapStore2 UI.
Covers ~97% of all translatable strings using proper pt-PT locale
(European Portuguese vocabulary and spelling).

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/geosolutions-it/MapStore2/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

Issue

What is the current behavior?
No Portuguese (pt-PT) translation exists in the official repository.

What is the new behavior?
Users can select Portuguese (pt-PT) as the interface language,
with ~97% of UI strings translated.

Breaking change

Does this PR introduce a breaking change?

• Yes, and I documented them in migration notes
• No

Other useful information

Translation covers all major UI sections including maps, layers, catalog,
widgets, annotations, print, timeline, style editor, and more.

[cla-bot]

In order to contribute to the MapStore project, the CLA (Contributor License agreement) should be sent signed to GeoSolutions. Please consult contributing rules at: https://github.com/geosolutions-it/MapStore2/wiki/Contributing-to-MapStore#contributing-code

[tdipisa]

Dear @huntsmarinho thank you so much for your contribution. Please notice that above as the CLA is necessary for allowing you to contribute for new updates. Thank you so much.

[cla-bot]

In order to contribute to the MapStore project, the CLA (Contributor License agreement) should be sent signed to GeoSolutions. Please consult contributing rules at: https://github.com/geosolutions-it/MapStore2/wiki/Contributing-to-MapStore#contributing-code

[tdipisa]

@huntsmarinho thank you so much for signing the CLA. We will proceed soon with the review.

[tdipisa]

Dear @huntsmarinho thank you so much for contributing to MS.
It seems there are ESlint failing checks for this PR. Can you please check and fix them? Thanks.