fix(practice): ensure badges are never taller than wide

Use fixed height with minWidth and pill-shaped border-radius so badges expand horizontally for multi-digit numbers while staying circular for single digits.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/components/practice/StartPracticeModal.tsx

@@ -614,8 +614,7 @@ export function StartPracticeModal({
                                   top: '-8px',
                                   right: '-8px',
                                   minWidth: '22px',
-                                  minHeight: '22px',
-                                  aspectRatio: '1 / 1',
+                                  height: '22px',
                                   display: 'flex',
                                   alignItems: 'center',
                                   justifyContent: 'center',
@@ -623,8 +622,8 @@ export function StartPracticeModal({
                                   fontWeight: 'bold',
                                   color: 'white',
                                   backgroundColor: 'green.500',
-                                  borderRadius: '50%',
-                                  padding: '2px',
+                                  borderRadius: '11px',
+                                  padding: '0 6px',
                                   boxShadow: '0 2px 4px rgba(0,0,0,0.2)',
                                 })}
                               >