#7234 improvement(ui): soften overflow fade

Summary

• shorten the canonical overflow fade from 18px to 16px
• keep the fade-only truncation treatment consistent across all consumers

Type of Change

• Improvement

Testing

• bunx vitest run packages/emcn/src/components/overflow-text/overflow-text.test.tsx
• bun run lint
• bun run apps/sim/scripts/check-block-registry.ts origin/staging
• bun run check:audits

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)