ui,i18n: complete Spanish translation

[creativefilmspy-maker]

Summary

This completes the Spanish (es_ES) translation currently tracked in the OpenSnitch UI catalog.

• Completed all 140 entries marked unfinished.
• Reviewed and improved partial Spanish text that was still marked unfinished.
• Preserved Python, Qt, and printf-style placeholders.
• Kept protocol names, identifiers, paths, and algorithm names technical where translating them
  could change their meaning.

Validation

• Active messages: 649.
• Finished: 649.
• Unfinished: 0.
• Empty active translations: 0.
• Placeholder mismatches: 0.
• lrelease-qt6: generated 649 finished and 0 unfinished translations.
• XML parsing and git diff --check: PASS.

The translation was also compiled and tested locally in the OpenSnitch 1.8.0 UI on Fedora. The
application, traffic graph, and visible Spanish interface were physically confirmed after login.

Related internationalization fix

Some dynamic UI strings are formatted before Qt performs its lookup, which can still cause an
English fallback even when a translation exists. A separate language-neutral pull request fixes
that code path and adds a regression test: #1651. Keeping the two changes separate makes this
catalog update easy to review and useful on its own.