docs: add Brazilian Portuguese onboarding

[rmcdaniel]

Advances #169 with the next agreed locale, Brazilian Portuguese (pt-BR).

Acceptance before publication

• Translate the complete eleven-guide onboarding journey already available in
  Spanish, plus home, navigation, search and sidebar descriptions.
• Preserve executable examples, API identifiers, artifact placeholders and
  English heading anchors. Review fluent Portuguese and technical meaning
  against current English source.
• Mark untranslated reference and 1.x pages clearly as English. Keep English,
  Ukrainian and Spanish usable, with correct canonical/alternate metadata.
• Extend the existing code-block/source-review check to the new locale.
• Pass all normal checks and representative desktop/mobile browser checks,
  then deploy and verify actual published routes before reporting delivery.

Current state

All eleven guides, Portuguese UI/navigation and source-review tracking are
implemented. The code-block check passes for both Spanish and Portuguese.
Review also corrected the shared parallel-activity example to call all()
instead of returning an unexecuted closure, and clarified that worker recovery
does not retry a terminal failed workflow. English, Ukrainian and Spanish
copies are updated together.

Qualification

• Full npm run build passes on Node 24 for English, Ukrainian, Spanish and
  Brazilian Portuguese, including strict links, source-review checks and the
  existing dependency/toolchain/search checks.
• All four normal GitHub checks pass at
  466456457628ecb46a1cdb10e4bbe0bffc51dc6f.
  Documentation CI
• Chromium checks pass at 1440×1000 and 390×844: all eleven Portuguese routes,
  canonical and all four alternate-language links, localized first-workflow
  navigation, expandable PHP/Python/Rust tabs and shared artifact values,
  accented recuperação search, stable anchors and relative fallback links.
• English reference and 1.x fallback notices, English markup, direct English
  links, all existing locales, desktop/mobile language switching and Portuguese
  homepage metadata pass with no browser runtime exceptions. Representative
  desktop/mobile images were inspected.

Published

Merged October 9 at 02:30 UTC as
541b1fa589fb4b0dbebe3575da8fbdc4fa7f22c1, with the same tested source tree.
All five merged-main checks and
Pages deployment
pass. The same desktop/mobile browser checks pass on the live website,
including all eleven Portuguese routes, accented search, fallback and language
switching. The completed branch is deleted and GitHub absence verified.

Portuguese introduction
and first workflow are live.
#169 stays open for Simplified Chinese and Japanese.

Terminology keeps workflow, worker, namespace and replay as technical terms.
Activities, signals, timers, queries and updates use atividade, sinal,
temporizador, consulta and atualização in prose. Code identifiers stay exact.