chore: UI and content tweaks — transparency copy, events subdomain, jua kali logo

[tylerkstevens]

Summary

A handful of small UI/content fixes in one branch:

• Transparency page copy: hero trimmed to the 501(c)(3)/EIN line plus "See our transparency documents below." on its own line. The closing CTA now says "Questions? Start at the FAQ." with a primary "Read the FAQ →" button to /faq (secondary still goes to contact).
• PageCTA component: new optional donateHref / contactHref props, defaulting to /donate and /contact — all other pages render exactly as before.
• Events now live at events.256foundation.org: the connect card on /community is renamed "Developer Calls" → "Dev Calls and other Events"; the footer Events Calendar link and both telehash "View Events Calendar" links point at the new subdomain. Forum upcoming-events URLs are gone from the site (README table and channel-list test updated to match).
• Assets: public/ecosystem/jua-kali.webp — white background flood-filled to transparency so the logo sits on the card background like the other ecosystem logos. Interior white details of the mark preserved; verified on magenta composite and in-browser.

Testing

• npm test — 66/66 pass
• npx eslint . — clean
• Manual: transparency page intro/CTA, FAQ button click-through, community card label/icon/href, telehash + footer links, logo rendering in light cards

Note: anyone who viewed /community recently may see the old white-box jua kali logo until the optimized-image cache expires or after a hard refresh — same URL, new bytes.