feat: recover portfolio pages from scratch workspaces

- Add base layouts (BaseLayout, BlogLayout, ProjectLayout)
- Add UI components (Header, Footer, Navigation, Card, Tag)
- Add About page with personal story
- Add Projects pages (index, detail)
- Add homepage content
- Add SEO files (robots.txt, webmanifest)

Work was done by agents in isolated workspaces.
Consolidated into main repo for proper git tracking.

public/site.webmanifest

@@ -0,0 +1,21 @@
+{
+  "name": "David Aragón - Indie Builder",
+  "short_name": "DA Portfolio",
+  "description": "Portfolio personal y blog de indie builder español",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#0a0e27",
+  "theme_color": "#60a5fa",
+  "icons": [
+    {
+      "src": "/android-chrome-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/android-chrome-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+}