feat: add language as post property (#151)

* feat: add language as post property

* update frontmatter.json

* style: remove extra space

* fix: remove unnecessary replacements

* feat: add `language` field to `new-post.js`

* style: format code style

* fix: use `siteConfig.lang` in `jsonLd`

* fix: use `siteConfig` when `entry.data` was empty

src/content/config.ts

@@ -9,6 +9,7 @@ const postsCollection = defineCollection({
     image: z.string().optional().default(''),
     tags: z.array(z.string()).optional().default([]),
     category: z.string().optional().default(''),
+    language: z.string().optional().default(''),
 
     /* For internal use */
     prevTitle: z.string().default(''),