Fix: Resolve nested anchor tag bug in project cards

[nirobnk]

• Restructured ProjectCard.astro to eliminate invalid nested anchors
• Separated card header and 'Go to Project' button into independent links
• Fixes clickability issue on activist.org, CircuitVerse, and Opensourcedesign cards
• Maintains proper cursor pointer behavior on all interactive elements

[Sean-Kenneth-Doherty]

I checked this locally with GITHUB_TOKEN=$(gh auth token) pnpm build; the build passes, and the generated card markup no longer wraps IssueList links inside the outer project-card link. That confirms the main nested-anchor bug is addressed.

Two small follow-ups before merge would make this safer:

• The new Card-Header-Link and Card-Link anchors both use target="_blank"; they should also include rel="noopener noreferrer" to avoid exposing window.opener.
• src/components/ProjectList.astro still reads card.querySelector(".Card-Real-Link") when building its client-side project list. This PR removes .Card-Real-Link, so that value becomes empty in the generated page. It looks unused today, but updating it to .Card-Link/.Card-Header-Link or removing the unused projectLink field would keep the script from silently going stale.