feat: add about, contact with map, legal pages and 404

- About page with identity cards and equipment lists (about.json)
- Contact page: station info, obfuscated e-mail, lazy Leaflet/OSM map
  with antenna tower marker and dark-mode tiles
- Privacy, license and disclaimer pages from a legal collection
- QRT-themed 404 page
- LICENSE (MIT) and LICENSE-CONTENT (CC BY-SA 4.0 legal code)
- Shared PageHeader and CodeCopy components

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

package.json

@@ -27,11 +27,13 @@
     "@tailwindcss/vite": "^4.3.3",
     "astro": "^7.4.0",
     "astro-icon": "^1.2.0",
+    "leaflet": "^1.9.4",
     "tailwindcss": "^4.3.3"
   },
   "devDependencies": {
     "@astrojs/check": "^0.9.10",
     "@tailwindcss/typography": "^0.5.20",
+    "@types/leaflet": "^1.9.22",
     "pagefind": "^1.5.2",
     "prettier": "^3.9.10",
     "prettier-plugin-astro": "^1.1.1",