feat(i18n): French and German localization (phase 5)

- Add full message catalogs and content for French (fr) and German (de)
- Implement ASCII canonical slugs for French and German routes
- Add language-specific search endpoints (/api/busca/fr, /api/busca/de)
- Configure strict 404 responses for /fr/livro and /de/livro
- Localize SEO, OpenGraph (fr_FR, de_DE), Twitter and JSON-LD schemas
- Add localized code example comments across 14 examples for fr and de
- Enable 'fr' and 'de' in ENABLED_LOCALES with root negotiation and redirect
- Extend test suite in check-i18n, smoke-imagem and verifica-vazamentos

Co-Authored-By: Antigravity <noreply@google.com>

scripts/check-i18n.mjs

@@ -134,6 +134,7 @@ const TECHNICAL_ALLOWLIST = new Set([
 	"Núcleos de CPU (Dual-Core vs Single-Core)",
 	"Bluetooth Classic (BR/EDR)",
 	"Ethernet MAC 10/100 Mbps",
+	"Séries ESP32",
 ]);
 
 function isTechnicalAllowlisted(val, path = "") {