Put the blog where people look for it

The blog was reachable only from a link in the footer, which is to say
hardly at all. Once there is a post:

- "Blog" joins the header menu, on desktop and in the mobile menu, on
  every page.
- The landing shows the three latest posts under "Novedades", with a
  link to the rest.

The post card moves into its own component, post-card, shared by the
blog (image beside the text) and the landing (image above).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

landing/src/app/core/copy.ts

@@ -136,6 +136,7 @@ export interface Copy {
     readMore: string;
     published: string;
     feed: string;
+    seeAll: string;
   };
   service: {
     eyebrow: string;
@@ -326,6 +327,7 @@ const es: Copy = {
     readMore: 'Leer',
     published: 'Publicado el',
     feed: 'Suscríbete por RSS',
+    seeAll: 'Ver todas las novedades',
   },
   service: {
     eyebrow: 'Servicio',
@@ -529,6 +531,7 @@ const en: Copy = {
     readMore: 'Read',
     published: 'Published on',
     feed: 'Subscribe via RSS',
+    seeAll: 'See all the news',
   },
   service: {
     eyebrow: 'Service',
@@ -732,6 +735,7 @@ const ca: Copy = {
     readMore: 'Llegir',
     published: 'Publicat el',
     feed: "Subscriu-t'hi per RSS",
+    seeAll: 'Veure totes les novetats',
   },
   service: {
     eyebrow: 'Servei',