Design: Question Stack Overflow Q&A layout

[melvincarvalho]

Design PR — edits app.js + app.css only (no app files touched).

• Question gets a Stack Overflow Q&A layout (class .card.qa-card)
  • Stat chips row: answer count + green accepted badge
  • Question title in bold, large
  • Question body as readable pre-wrap text
  • Author + date meta line with accent-colored author name
  • Green-tinted accepted answer panel with checkmark header and body text
  • Dark mode support

Gate: 324 apps pass. Task: #IssDesign2_Question.