fix: standardize translation file names and add 11 new locales (v1.0.5)

- Rename all .po files to use wp-bootstrap- prefix (WordPress convention)
- Add 11 new locale translations (de_CH_informal, de_DE, de_DE_informal,
  en_GB, es_ES, fr_CH, it_CH, it_IT, nl_NL, pl_PL, pt_PT)
- Total: 13 locales + en_US base = 14 supported languages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -17,7 +17,7 @@ A modern WordPress Block Theme built from scratch with Bootstrap 5. Features res
 - **Widget Area** -- Sidebar widget area manageable via WordPress admin, with built-in fallback
 - **Accessibility** -- Skip-to-content link, ARIA labels, `aria-current` on active items, screen reader announcements
 - **RTL Support** -- Right-to-left language support with logical CSS properties
-- **Translation Ready** -- Full i18n support with `en_US`, `de_CH`, and `fr_FR` translations
+- **Translation Ready** -- Full i18n support with 14 locales (en_US, de_CH, de_CH_informal, de_DE, de_DE_informal, en_GB, es_ES, fr_CH, fr_FR, it_CH, it_IT, nl_NL, pl_PL, pt_PT)
 - **Responsive** -- Mobile-first design with Bootstrap's responsive grid
 
 ## Requirements