feat(i18n): complete Portuguese, add Brazilian Portuguese (pt_BR)

Fill the ~74 UI strings pt.i18n.json was missing (saved searches, label
scanning, Plantaré, lot history), then add pt_BR as a proper Brazilian
variant rather than a copy of European Portuguese: tu/teu/tua -> você/
seu/sua with matching verb conjugation, partilhar -> compartilhar, and
Guardar -> Salvar for UI actions (seed-saving keeps "guardar", the
correct term in both variants). Wires AppLocale.ptBr into the language
picker and regenerates slang output.

apps/app_seeds/lib/i18n/de.i18n.json

@@ -95,6 +95,7 @@
     "langEs": "Español",
     "langEn": "English",
     "langPt": "Português",
+    "langPtBr": "Português (Brasil)",
     "langAst": "Asturianu",
     "about": "Über",
     "aboutText": "Lokale, verschlüsselte Saatgutbank für traditionelle Samen. AGPL-3.0.",
@@ -147,9 +148,9 @@
     "license": "Lizenz",
     "licenseValue": "AGPL-3.0",
     "website": "Webseite",
-  "sourceCode": "Quellcode",
-  "translate": "Beim Übersetzen helfen",
-  "translateSubtitle": "Hilf, Tane in deine Sprache zu bringen",
+    "sourceCode": "Quellcode",
+    "translate": "Beim Übersetzen helfen",
+    "translateSubtitle": "Hilf, Tane in deine Sprache zu bringen",
     "openSourceLicenses": "Open-Source-Lizenzen",
     "openSourceLicensesSubtitle": "Bibliotheken von Drittanbietern und ihre Lizenzen",
     "copyright": "© {years} Comunes Association, unter AGPLv3"
@@ -723,4 +724,4 @@
     "manageEmpty": "Du hast niemanden blockiert",
     "unblock": "Entsperren"
   }
-}
+}