feat(05-01): create content.config.ts with bilingual blog collections

- Define blog_fr collection: fr/blog/**/*.md → prefix /blog (FR default locale)
- Define blog_en collection: en/blog/**/*.md → prefix /en/blog (EN prefixed)
- Add Zod schema: title, description, date (required) + tags, image (optional)

content.config.ts

@@ -0,0 +1,24 @@
+import { defineContentConfig, defineCollection, z } from '@nuxt/content'
+
+const blogSchema = z.object({
+  title: z.string(),
+  description: z.string(),
+  date: z.string(),
+  tags: z.array(z.string()).optional(),
+  image: z.string().optional(),
+})
+
+export default defineContentConfig({
+  collections: {
+    blog_fr: defineCollection({
+      type: 'page',
+      source: { include: 'fr/blog/**/*.md', prefix: '/blog' },
+      schema: blogSchema,
+    }),
+    blog_en: defineCollection({
+      type: 'page',
+      source: { include: 'en/blog/**/*.md', prefix: '/en/blog' },
+      schema: blogSchema,
+    }),
+  },
+})