fix(i18n): extract navigation links module and restore verbatim pt footer

- Move getLocalizedHref, LOCALES, and CANONICAL_ROUTES to i18n/links.js to resolve SSR 500 error on home
- Import from @/i18n/links in page.jsx, Header.jsx, Footer.jsx, and LanguageSelector.jsx
- Restore exact production footer texts, author links, and SVG icons in pt
- Verify 100% visible text parity on all pt pages against production with cmp-pt.py

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

components/Header.jsx

@@ -5,7 +5,8 @@ import { createPortal } from "react-dom";
 import Link from "next/link";
 import Logo from "@/components/Logo";
 import SearchDialog from "@/components/SearchDialog";
-import LanguageSelector, { LOCALES, getLocalizedHref } from "@/components/LanguageSelector";
+import LanguageSelector from "@/components/LanguageSelector";
+import { LOCALES, getLocalizedHref } from "@/i18n/links";
 import { usePathname } from "next/navigation";
 import { useTheme } from "next-themes";
 import {