Add CodeMash, QCon, and Scala Days conference data

[arthurgervais]

Summary

• Add CodeMash, QCon, and Scala Days rows to the conference dataset.
• Preserve the existing README table schema and use conservative SEA/speaker-policy values where I did not find a public SEA commitment.

Sources and rationale

• CodeMash: FAQ identifies CodeMash Conference as an Ohio non-profit and organizer context; speaker-benefits page lists a four-day pass, hotel/housing support, and a precompiler honorarium.
  • https://codemash.org/faq/
  • https://codemash.org/call-for-speakers-announcement/
• Scala Days: 2026 site and Scala announcement identify the Berlin event and Scala Center / Plain Schwarz partnership; CFP/ticket pages describe talks/labs/workshops and attendee tickets, with no public SEA, reimbursement, or honorarium commitment found.
  • https://scaladays.org/
  • https://www.scala-lang.org/blog/2026/03/26/scala-days-2026.html
  • https://www.scala-lang.org/blog/2026/04/30/scala-days-2026-cfp.html
  • https://tickets.plainschwarz.com/scaladays26/
• QCon: C4Media identifies itself as provider of QCon conferences; QCon SF support page describes travel/accommodation support; historical speaker info confirms QCon-covered conference fee. No public SEA or speaker honorarium commitment found.
  • https://c4media.com/diversity
  • https://qconsf.com/qcon-cares
  • https://qconnewyork.com/ny2012/qcon-nyc-2012/speakerinformation/index.html

Verification

• git diff --check
• Verified all conference dataset rows still have the same Markdown column count.

Demo note: this is a static README data update; the PR diff is the demo surface for review.

/claim #4
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[arthurgervais]

This same README update also adds CodeMash and QCon rows for the two matching tracker issues.

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