v0.4.1: visual design pass on the tray icon digits

0.4.0's seven-segment redesign fixed legibility but not polish -- real
feedback on a fresh screenshot: "readable now, but still doesn't look
professional." Rounded (not raw-rectangle) segments with soft
anti-aliased edges, a small gap between adjoining segments so they read
as distinct rather than fused, and a refined color palette (flatter,
closer to iOS/macOS system status colors) instead of fully-saturated
primary hues that read more like hazard-sign colors than a status badge.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>