Add an English translation of the corralito training-courses page

It was deliberately left Italian-only when /en support was first added;
now translated and following the same thin-page + shared-view pattern
as every other route, with the nav link and language switch no longer
special-casing it.

frontend/app/layouts/default.vue

@@ -27,8 +27,8 @@ const strings = computed(() => STRINGS[locale.value])
           <ul>
             <li><NuxtLink :to="localePath(locale, '/')">{{ strings.navHome }}</NuxtLink></li>
             <li><NuxtLink :to="localePath(locale, '/blog')">{{ strings.navBlog }}</NuxtLink></li>
-            <li v-if="locale === 'it'">
-              <NuxtLink to="/come-difendersi-dal-corralito">{{ strings.navCorralito }}</NuxtLink>
+            <li>
+              <NuxtLink :to="localePath(locale, '/come-difendersi-dal-corralito')">{{ strings.navCorralito }}</NuxtLink>
             </li>
           </ul>
         </div>
@@ -55,8 +55,8 @@ const strings = computed(() => STRINGS[locale.value])
           <ul>
             <li><NuxtLink :to="localePath(locale, '/')">{{ strings.navHome }}</NuxtLink></li>
             <li><NuxtLink :to="localePath(locale, '/blog')">{{ strings.navBlog }}</NuxtLink></li>
-            <li v-if="locale === 'it'">
-              <NuxtLink to="/come-difendersi-dal-corralito">{{ strings.navCorralito }}</NuxtLink>
+            <li>
+              <NuxtLink :to="localePath(locale, '/come-difendersi-dal-corralito')">{{ strings.navCorralito }}</NuxtLink>
             </li>
           </ul>
         </nav>