[codex] Structure homepage news and publications

[Ridealist]

Summary

• Move homepage News into structured _data/news.yml.
• Add structured Publications data and reusable homepage includes.
• Add homepage publication styling for light, dark, and mobile layouts.
• Update homepage profile links with LinkedIn, Google Scholar, and CV.
• Use Academicons for Google Scholar and CV icons.

Impact

• Homepage News and Publications can now be maintained through data files instead of inline homepage markup.
• Profile links now reflect the requested public academic and contact links.
• Existing blog routes and post/category behavior are unchanged.

Closes #19
Closes #20

Not in scope

• [Academic Homepage 3/3] 블로그 글과 카테고리 페이지 톤을 새 홈 UI와 맞추기 #21 blog/category page tone matching remains separate.

Validation

• bundle exec jekyll build