feat: Upgrade to Astro 6

- Astro 5.x → Astro 6.1.2
- @astrojs/node 9.x → 10.x
- Content config: src/content/config.ts → src/content.config.ts
- Update to glob loader pattern for content collections
- Replace post.slug with post.id for content loader
- Replace post.render() with render(post)

package.json

@@ -16,11 +16,11 @@
     "db:seed": "astro db seed"
   },
   "dependencies": {
-    "@astrojs/db": "^0.20.0",
-    "@astrojs/node": "^9.5.4",
+    "@astrojs/db": "^0.20.1",
+    "@astrojs/node": "^10.0.4",
     "@astrojs/sitemap": "^3.7.2",
     "@tailwindcss/vite": "^4.2.1",
-    "astro": "^5.17.1",
+    "astro": "^6.1.2",
     "astro-consent": "^1.0.17",
     "better-sqlite3": "^12.8.0",
     "drizzle-orm": "^0.45.1",