Simplify events page calendar UX

[msaroufim]

Summary

• replace the combined copy-and-redirect action with a clear two-step subscription flow
• display the full lecture calendar feed URL with a dedicated Copy URL button and status feedback
• provide a separate link to Google Calendar’s supported “From URL” settings page
• remove the redundant per-lecture “View on Discord (Add to Calendar)” links
• hide the entire in-person events section when no upcoming events exist

Why

The working subscription flow was still unclear because the feed URL and Google Calendar step were coupled, while individual lecture links exposed a competing calendar path. The page also showed an empty in-person section when there was nothing actionable in it.

Impact

Users get one clear way to subscribe to all upcoming lectures, can see exactly which .ics URL Google Calendar needs, and no longer see redundant calendar links or an empty in-person events section.

Validation

• npm run lint
• npm run build
• visually verified the empty in-person section is absent
• verified the Copy URL button changes to Copied