Replace hardcoded FTL_TO_URL and LANG_NAMES maps with dynamic
detection. ftl_to_url() derives URL codes from FTL filenames
(e.g., fr-FR -> fr, zh-Hans -> zh-Hans). locale_display_name()
uses python3+babel for native language names with fallback to the
code itself. New locales are now picked up automatically without
editing the scripts.
The URL matching regex only accepted two-letter codes or two-letter
plus two uppercase (e.g., pt-BR), missing codes like zh-Hant with
longer suffixes. Use [a-zA-Z]+ after the hyphen to match all codes.
- Scan coreutils-l10n for available locales instead of hardcoding
- Fix language switcher to use relative path replacement so it works
with both deployed and local file:// URLs
- Move links into the existing .additional div for better layout
Sylvestre Ledru