i18n(pt-BR): complete UI localization (100% coverage)

[magisph]

Hi, @Fangyuan025

Following up on the initial batch in #7, this PR completes the Brazilian Portuguese (pt-BR) localization, bringing the UI coverage to 100% (translating the remaining 351 keys).

• Translated all remaining modules.
• Preserved technical terms in English,
• Adjusted string lengths to fit UI components and verified syntax (npm run typecheck passes cleanly).
• As agreed, agent/model prompts were left untouched.

[Fangyuan025]

Merged — thank you. I checked it key by key: no key added or removed, en and zh byte-identical to before, and every translated string carries exactly the placeholders its English original does. I also ran the UI in pt-BR at 900px and 780px; nothing clips or overflows (Ignorar aprovação wraps inside its chip at the narrow end, which the layout absorbs).

One thing for a follow-up if you'd like it: coverage is 547/559 rather than 100%. The twelve that are untranslated are exactly the strings carrying a {placeholder} — I suspect your pass skipped those. Two of them are model prompts (todayNote, attachInstruction) and are correctly left in English. The other ten are UI:

confirmDeleteModel  updateAvailable  storeDaysAgo  charsLabel
kbFolderConfirm     hwThreads        hwLayersOn    oomPartial
gpuCrashCapped      ctxClamped

They fall back to English, so nothing is broken — the locale structure is built for partial coverage. No rush.