feat(seo): 다국어 포스트 URL을 /en/, /ja/ 계층 구조로 변경

영어 포스트 → /en/YYYY/MM/DD/slug/, 일본어 → /ja/YYYY/MM/DD/slug/
기존 URL은 jekyll-redirect-from으로 리다이렉트 처리
본문 하드코딩 링크 152개 일괄 수정, hreflang 태그 업데이트

Author: realcoding2003

_config.yml

@@ -42,6 +42,7 @@ plugins:
   - jekyll-sitemap
   - jekyll-seo-tag
   - jekyll-paginate
+  - jekyll-redirect-from
 
 # Pagination
 paginate: 30

_layouts/default.html

@@ -26,8 +26,8 @@
       {%- endif -%}
       {%- assign date_path = page.date | date: "/%Y/%m/%d/" -%}
       <link rel="alternate" hreflang="ko" href="{{ site.url }}{{ date_path }}{{ base_slug }}/" />
-      <link rel="alternate" hreflang="en" href="{{ site.url }}{{ date_path }}{{ base_slug }}-en/" />
-      <link rel="alternate" hreflang="ja" href="{{ site.url }}{{ date_path }}{{ base_slug }}-ja/" />
+      <link rel="alternate" hreflang="en" href="{{ site.url }}/en{{ date_path }}{{ base_slug }}-en/" />
+      <link rel="alternate" hreflang="ja" href="{{ site.url }}/ja{{ date_path }}{{ base_slug }}-ja/" />
       <link rel="alternate" hreflang="x-default" href="{{ site.url }}{{ date_path }}{{ base_slug }}/" />
     {% else %}
       {%- assign base_path = page.url | remove: '/en' | remove: '/ja' -%}

_posts/2020-03-15-why-i-use-docker-en.md

@@ -7,6 +7,9 @@ tags: [Docker, Container, Deployment, DevEnvironment, DevOps]
 author: "Kevin Park"
 lang: en
 excerpt: "I switched every project to Docker two years ago. Low barrier to entry, easy deployments... but is it really all upside?"
+permalink: /en/:year/:month/:day/:title/
+redirect_from:
+  - /2020/03/15/why-i-use-docker-en/
 ---
 
 # My Honest Review After Using Docker for Every Project for 2 Years

_posts/2020-03-15-why-i-use-docker-ja.md

@@ -7,6 +7,9 @@ tags: [Docker, コンテナ, デプロイ, 開発環境, DevOps]
 author: "Kevin Park"
 lang: ja
 excerpt: "2年前からすべてのプロジェクトをDocker基盤に切り替えました。導入障壁が低くてデプロイも楽ですが、本当にメリットだけでしょうか？"
+permalink: /ja/:year/:month/:day/:title/
+redirect_from:
+  - /2020/03/15/why-i-use-docker-ja/
 ---
 
 # Dockerを2年間すべてのプロジェクトで使ってみた正直な感想

_posts/2020-03-16-developer-laziness-burnout-en.md

@@ -7,6 +7,9 @@ tags: [Developer, Burnout, Laziness, Growth, Experience]
 author: "Kevin Park"
 lang: en
 excerpt: "I still love coding, but my hands just won't move. The architecture is all planned out in my head, yet execution feels impossible. Am I the only one?"
+permalink: /en/:year/:month/:day/:title/
+redirect_from:
+  - /2020/03/16/developer-laziness-burnout-en/
 ---
 
 # When Coding Is Fun But Your Hands Won't Move

_posts/2020-03-16-developer-laziness-burnout-ja.md

@@ -7,6 +7,9 @@ tags: [開発者, バーンアウト, 怠惰, 自己成長, 開発経験]
 author: "Kevin Park"
 lang: ja
 excerpt: "開発が嫌いになったわけじゃないのに手が動かない。頭の中では設計が完了しているのに実行できない。これって自分だけでしょうか？"
+permalink: /ja/:year/:month/:day/:title/
+redirect_from:
+  - /2020/03/16/developer-laziness-burnout-ja/
 ---
 
 # 開発は楽しいのに手が動かない

_posts/2020-04-20-cloud-vs-onpremise-server-en.md

@@ -7,6 +7,9 @@ tags: [Server, Cloud, AWS, OnPremise, IDC, Migration]
 author: "Kevin Park"
 lang: en
 excerpt: "New projects go to the cloud. Old ones stay on IDC servers. I keep telling myself I'll migrate them... but somehow never do."
+permalink: /en/:year/:month/:day/:title/
+redirect_from:
+  - /2020/04/20/cloud-vs-onpremise-server-en/
 ---
 
 # The Transition From On-Premise to Cloud

_posts/2020-04-20-cloud-vs-onpremise-server-ja.md

@@ -7,6 +7,9 @@ tags: [サーバー, クラウド, AWS, オンプレミス, IDC, マイグレー
 author: "Kevin Park"
 lang: ja
 excerpt: "新しいプロジェクトはクラウド、既存のものはIDCそのまま。毎回移行しようと思いつつ応急処置だけして先延ばしにしている。"
+permalink: /ja/:year/:month/:day/:title/
+redirect_from:
+  - /2020/04/20/cloud-vs-onpremise-server-ja/
 ---
 
 # オンプレミスからクラウドへの過渡期

_posts/2020-04-21-mysql-uuid-usage-en.md

@@ -7,6 +7,9 @@ tags: [MySQL, UUID, Security, Database, PHP]
 author: "Kevin Park"
 lang: en
 excerpt: "Using auto_increment PKs directly in URLs gets flagged in every security audit. But replacing all PKs with UUIDs is wildly impractical. Here's the realistic middle ground."
+permalink: /en/:year/:month/:day/:title/
+redirect_from:
+  - /2020/04/21/mysql-uuid-usage-en/
 ---
 
 # Why You Shouldn't Expose Auto Increment PKs in URLs

_posts/2020-04-21-mysql-uuid-usage-ja.md

@@ -7,6 +7,9 @@ tags: [MySQL, UUID, セキュリティ, データベース, PHP]
 author: "Kevin Park"
 lang: ja
 excerpt: "auto_incrementのPKをそのままURLに使うと、セキュリティ監査で毎回指摘される。かといってPKを全部UUIDに変えるのは非効率すぎる。現実的な妥協案をまとめました。"
+permalink: /ja/:year/:month/:day/:title/
+redirect_from:
+  - /2020/04/21/mysql-uuid-usage-ja/
 ---
 
 # Auto Increment PKをURLに露出してはいけない理由