Add left sidebar navigation to news page

[weng271190436]

Summary

Adds a left sidebar with clickable date index to the news page, matching the layout used on science.html and other pages.

Fixes #203

Changes

news.html

• Changed layout from span12 to span3 (sidebar) + span9 (content)
• Added #news-nav sidebar element with loading spinner
• Added missing jquery.pjax.js include

js/main.js

• Updated loadFullNewsFeed() to populate the sidebar nav with clickable dates
• Each date links to an anchor on the corresponding article
• Gracefully handles case where sidebar doesn't exist (backwards compatible)

Screenshots

The sidebar shows article dates (e.g. "Apr 5, 2026") — clicking scrolls to that article.

Testing

1. python3 -m http.server 8000
2. Open http://localhost:8000/news.html
3. Verify sidebar appears on left with dates
4. Click a date — page scrolls to that article

[pgleeson]

Thanks for this @weng271190436. Did you say this also fixes the issue at #202? I'm still getting that issue testing this locally...

[weng271190436]

@pgleeson sorry I was mistaken. I thought I fixed it by including jquery.pjax.js. But after investigating further I realized that the issue was due to flakiness of api.allorigins.win. I don't think think there is a fix if api.allorigins.win is not reliable.

I updated the description to remove the incorrect claim that I fixed #202. Thanks for trying out locally and pointing that out