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/ui/post-card.scss

@@ -0,0 +1,77 @@
+:host {
+  display: block;
+  height: 100%;
+}
+
+.post-card {
+  display: grid;
+  grid-template-rows: auto 1fr;
+  height: 100%;
+  overflow: hidden;
+  border-radius: var(--pi-theme-card-radius, 1.5rem);
+  box-shadow: var(--pi-theme-card-shadow, none);
+}
+
+// Beside the text rather than above it, and only when there is an image:
+// without one the text would sit in the image's column with the rest empty.
+:host(.post-card--row) .post-card--media {
+  @media (min-width: 768px) {
+    grid-template-rows: none;
+    grid-template-columns: minmax(0, 20rem) minmax(0, 1fr);
+  }
+}
+
+// The `<img>` belongs to `app-api-image`, so a scoped rule cannot reach it.
+.post-card__media ::ng-deep img {
+  display: block;
+  width: 100%;
+  height: 100%;
+  aspect-ratio: 16 / 10;
+  object-fit: cover;
+}
+
+.post-card__body {
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+  padding: 1.5rem 1.75rem;
+}
+
+.post-card__date {
+  font-size: 0.8125rem;
+  color: color-mix(in srgb, currentColor 68%, transparent);
+}
+
+.post-card__title {
+  margin: 0;
+  font-size: 1.25rem;
+  font-weight: 700;
+  line-height: 1.25;
+
+  :host(.post-card--row) & {
+    font-size: 1.375rem;
+  }
+
+  a {
+    color: inherit;
+    text-decoration: none;
+
+    &:hover {
+      text-decoration: underline;
+    }
+  }
+}
+
+.post-card__excerpt {
+  margin: 0;
+  line-height: 1.6;
+  color: color-mix(in srgb, currentColor 68%, transparent);
+}
+
+.post-card__more {
+  margin-top: auto;
+  padding-top: 0.5rem;
+  color: var(--pi-color-primary);
+  font-weight: 600;
+  text-decoration: none;
+}