feat(split): unify edge styles and add torn/pixel

[CodeWithDennis]

Summary

• Unify split Style controls so Vertical, Horizontal, and Diagonal share one edge-style list
• Add Torn and Pixel edges (deterministic noise so wipe video does not flicker)
• Bring wavy / zigzag / scallop / soft to axis layouts (not only diagonal)

Key changes

• patterns.js
  • hashNoise for stable torn/pixel edges across frames
  • Axis painters for wavy, zigzag, scallop, soft/fade, torn, pixel
  • Diagonal paintAngledSplit gains torn + pixel
• app.js
  • Single splitStyle (+ splitStyles) for all split layouts
  • Keep writing diagonalStyle for preset backward compatibility
  • Map legacy fade → soft when loading presets
• app.blade.php
  • One Style + Density block for any split layout; Angle only for Diagonal
• README feature line updated

Behavior / impact

Style	Notes
Straight	Hard edge (default)
Wavy / Zigzag / Scallop	Density controls frequency/amplitude
Soft	Gradient fade (legacy preset fade maps here)
Torn	Irregular ripped edge
Pixel	Stair-step digital edge

• Density slider shows for every style except Straight and Soft
• Wipe / transition export continues to animate splitPosition through these masks
• Overlap layouts unchanged

Test plan

• Vertical + each style (Straight → Pixel); density affects wavy/zigzag/scallop/torn/pixel
• Horizontal + each style
• Diagonal + each style; Angle still works; Soft has no density slider
• Wipe video preview with Torn and Pixel (edge must not flicker frame-to-frame)
• Save preset with Zigzag on Vertical, reload, style restores
• Old preset with diagonalStyle: wavy still applies
• Overlap UI unchanged (no Style edge list)
• npm run build succeeds; hard-reload NativePHP/browser