Add comprehensive styling system for consistent DX across commands:
- Tailwind colour palette as named constants (30+ colours)
- Unicode symbols for status indicators, arrows, tree chars
- New styles: InfoStyle, AccentStyle, CodeStyle, NumberStyle, etc.
- Box styles with rounded borders for panels
- Helper functions: Success(), Error(), StatusLine(), KeyValue(), etc.
- Table struct with auto-width column rendering
Also:
- Fix cmd/build to use shared styles instead of duplicating
- Update cmd/dev/dev_health to use StatusLine() helper
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>