Add and wire extended site env config

lib/config.ts

@@ -5,5 +5,26 @@ export const siteConfig = {
     process.env.NEXT_PUBLIC_SITE_DESCRIPTION ||
     'Personal homepage and blog.',
   url: process.env.NEXT_PUBLIC_SITE_URL || 'http://localhost:3000',
-  author: process.env.NEXT_PUBLIC_SITE_AUTHOR || 'Your Name'
+  author: process.env.NEXT_PUBLIC_SITE_AUTHOR || 'Your Name',
+  tagline:
+    process.env.NEXT_PUBLIC_SITE_TAGLINE ||
+    '這裡是我的個人首頁與技術 Blog。',
+  postsPerPage:
+    Number(process.env.NEXT_PUBLIC_POSTS_PER_PAGE) > 0
+      ? Number(process.env.NEXT_PUBLIC_POSTS_PER_PAGE)
+      : 5,
+  defaultLocale: process.env.NEXT_PUBLIC_DEFAULT_LOCALE || 'zh-TW',
+  social: {
+    twitter: process.env.NEXT_PUBLIC_TWITTER_HANDLE || '',
+    github: process.env.NEXT_PUBLIC_GITHUB_URL || '',
+    linkedin: process.env.NEXT_PUBLIC_LINKEDIN_URL || '',
+    email: process.env.NEXT_PUBLIC_EMAIL_CONTACT || ''
+  },
+  ogImage: process.env.NEXT_PUBLIC_OG_DEFAULT_IMAGE || '/assets/og-default.jpg',
+  twitterCard:
+    (process.env.NEXT_PUBLIC_TWITTER_CARD_TYPE as
+      | 'summary'
+      | 'summary_large_image'
+      | undefined) || 'summary_large_image',
+  analyticsId: process.env.NEXT_PUBLIC_ANALYTICS_ID || ''
 };