D3.js SVG Pattern and Texture Library

Build a library of SVG patterns for accessible data visualization:

Use Cases:
- Distinguish categories without color alone
- Print-friendly visualizations
- Add visual texture and interest
- Support color blind viewers

Pattern Types Needed:

1. Line Patterns
   - Horizontal lines
   - Vertical lines
   - Diagonal (45°, -45°)
   - Crosshatch
   - Variable spacing

2. Dot Patterns
   - Regular grid
   - Offset/brick pattern
   - Variable density
   - Variable size

3. Shape Patterns
   - Triangles
   - Squares
   - Circles
   - Custom shapes

4. Complex Patterns
   - Checker
   - Herringbone
   - Wave
   - Custom brand patterns

Pattern Configuration:
- Size: [pattern tile dimensions]
- Stroke: [width, color]
- Fill: [background, foreground]
- Opacity: [transparency levels]
- Scale: [responsive sizing]

Integration with Charts:
- Bar chart fills
- Area chart fills
- Pie/donut segments
- Map regions
- Legend representation

Accessibility Requirements:
- Sufficient contrast
- Pattern distinctiveness
- Screen reader alternatives

Provide:
- Reusable pattern generator functions
- Pattern definitions for common needs
- Usage examples with D3.js charts
- CSS fallbacks for browsers