Add CodeMash, QCon, and Scala Days conference data

[AmanKishore]

/claim #4
/claim #10
/claim #11

Adds current rows for Scala Days, CodeMash, and QCon to the conference tracker and keeps the dataset table sorted by conference name as requested in the contributing notes.

Source notes:

• CodeMash: official CodeMash speaker benefits document lists a hotel reservation/housing credit, a four-day pass, and a precompiler honorarium. I used No for SEA because I did not find a public SEA commitment.
• QCon: public QCon speaker information lists covered conference registration and hotel support for non-local speakers. I used No for SEA and Never for compensation because I did not find public commitments for either.
• Scala Days: official Scala Days 2026 CFP confirms current conference identity, organizer context, and formats. I used conservative values where I did not find public SEA, reimbursement, or compensation commitments.

Verification:

• git diff --check
• Ruby table column count check: 15 table rows have expected column count

[AmanKishore]

/claim #4
/claim #10
/claim #11