pyfly by example: OAuth client APIs, English and Spanish

The English and Spanish editions of pyfly by example now cover the standalone OAuth code-exchange and refresh APIs, native HTTP token endpoints, and HTTP Basic authentication for confidential clients. The examples explain public-client code exchange, authenticated confidential-client refresh, the server audience, and recovery after an uncertain refresh result.

This book edition accompanies PyFly v26.10.03. It preserves the framework package version and its existing release assets.

Downloads include both languages in PDF and EPUB, books.sha256.json with the exact source commit and four asset hashes, and SHA256SUMS for all five files.

Qualified book source: 2ef77398357276e98563a37bd058ee4e74922cbd (PR #184). Source tree: 70f81bdca12fff7d189fc5789fd931e7131a0b9d.

Validation: 49 native ASGI/TCP contract cases, 83 book tests, 31 Python listing files per language, strict documentation build, and configured lint/format. The revised security sections and nearby PDF page transitions were reviewed in both languages; this was not a manual review of every book page. PR CI passed before merge, including Python 3.12, Python 3.13, SQLAlchemy 2.0, and browser/installed-distribution checks. Live-infrastructure lanes were skipped by the pull-request workflow.