feat(i18n): add Brazilian Portuguese (pt-BR) locale and localize hardcoded dashboard strings

[fernandomarcius]

Summary

Adds Brazilian Portuguese (pt-BR) as a supported output/UI language, and moves the dashboard's remaining hardcoded English strings into the locale files so every supported language renders a fully translated UI.

pt-BR locale

• packages/dashboard/src/locales/pt-BR.ts — full UI translation; resolveLocaleKey maps pt, pt-BR, pt_br, portuguese, brazilian-portuguese → pt-BR.
• skills/understand/locales/pt-BR.md — output guidelines (tags, summary style, technical terms, layer names) injected when --language pt-BR.
• skills/understand/SKILL.md — portuguese now normalizes to pt-BR; a bare pt uses the pt-BR guidance file.
• README + translated READMEs list pt-BR among supported languages (same pattern as feat(i18n): add Vietnamese (vi) locale support #709).

Hardcoded strings → locales (applies to all 8 locales, not only pt-BR)

• 125 new keys (new sections graphNodes, graphView, loadErrors, staleness, nodeTypeNames, edgeCategoryNames), plus wiring of existing-but-unused keys (ariaLabels.*, nodeTypeFilter.*, tokenGate.*, warningBanner.*, projectOverview.simple/moderate/complex).
• Complexity badges, node-type names, edge categories and edge labels are now localized via src/utils/i18nLabels.ts instead of rendering raw enum values (complex, LAYER, files, Click to explore →, …).
• Count/interpolated messages are functions so each language can apply its own plural rules (e.g. Russian one/few/many); search.result → search.resultCount(n).
• TokenGate renders before config.json is read, so it is wrapped in an I18nProvider that follows navigator.language; resolveLocaleKey now falls back to the base language (ja-JP → ja, ko-KR → ko).
• locales.test.ts: the key-shape helper used to drop leaf keys, so it compared nothing; it now compares every leaf and its kind (string vs function) across all 8 locales.

Intentionally left in English: the "Copy Issues" payload (meant for GitHub/agents), core validator / elk-layout diagnostics, raw server/exception error details, theme preset names, key names in the shortcuts table, and console logs.

Linked issue(s)

None.

How I tested this

• Ran /understand --language pt-BR flow on a ~560-file Rust workspace (3.8k nodes) and opened the dashboard: onboarding, persona selector, layer cards (CAMADA · Complexa · 29 arquivos · Clique para explorar →), filters, search, diff toggle, tour panel and code viewer all render in pt-BR; switching outputLanguage back to en restores English.

• Same CI sequence locally, all green:

• pnpm lint

• pnpm --filter @understand-anything/core test (799 passed, 4 skipped)

• pnpm test (1013 passed)

• pnpm --filter @understand-anything/core build, @understand-anything/skill build, understand-anything-viewer build, dashboard tsc -b + vite build

• python -m unittest tests.skill.understand.test_merge_batch_graphs tests.skill.understand.test_merge_subdomain_graphs tests.skill.knowledge.test_parse_knowledge_base (106 tests OK)

• Manual smoke test (described above)

Versioning

• Version bumped in all five manifests, OR
• N/A — left for the maintainer to bump on merge (same as the vi locale in feat(i18n): add Vietnamese (vi) locale support #709)