Fix UI issues: spacing, hover, reload, checkboxes, share button
1. Game list spacing: Fixed inconsistent game item heights by using
flexbox gap and making game-info flex: 1
2. Board hover: The interactive check was already correct - verified
hover only shows when it's your turn
3. Move submission: Removed page reload after moves/passes - now
updates local state directly. Only reloads if game ends (double-pass)
4. Stone-style checkboxes: Styled "My games" and "Your turn" checkboxes
to look like Go stones (white unchecked, black checked)
5. Share button: Made lighter/subtler with cloud background and border,
replaced butterfly emoji with Bluesky SVG logo, shortened to "Share"
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>