feat(i18n): register Brazilian Portuguese as a locale

Add pt-BR to the locale list and everything that hangs off it: the
client loader, Intl and date-fns mapping, the reply-language footers of
the Coach and insights prompts (English body, pt-BR footer, the same
path Korean and Dutch take), the citation-coverage normative words, the
no-key fallback copy, the AUDIT-C standard-drink line, country labels,
period search, CSV yes/no cells and the Telegram bare-word aliases.

The locale enums in the extract, managed-profile and record-settings
schemas now derive from the locale list instead of repeating it, and
the five notification and login-alert routes share one isLocale guard
instead of hand-rolled chains, so a later locale is one edit there.
A language tag is matched exactly and case-insensitively before its
primary subtag, so pt-BR and pt-PT browsers land on the Portuguese
bundle rather than English, and AUDIT-C no longer cuts a region tag to
two letters.

PHQ-9, GAD-7 and WHO-5 are not marked validated for pt-BR: the wording
has not been read against the published Brazilian forms, so readers get
the English items plus the existing note.

src/components/ui/calendar-locale.ts

@@ -1,4 +1,4 @@
-import { de, enUS, es, fr, it, ko, nl, pl } from "date-fns/locale";
+import { de, enUS, es, fr, it, ko, nl, pl, ptBR } from "date-fns/locale";
 import type { Locale as DateFnsLocale } from "date-fns";
 
 import type { Locale } from "@/lib/i18n/config";
@@ -25,6 +25,8 @@ export function resolveDateFnsLocale(locale: Locale): DateFnsLocale {
       return ko;
     case "nl":
       return nl;
+    case "pt-BR":
+      return ptBR;
     default:
       return enUS;
   }