Add AddGrain and TCanny plugins to Windows deps

- AddGrain r10: Film grain generation for restoration
- TCanny r14: Canny edge detection filter
- Update download-deps-windows.ps1 with plugin sources
- Document new plugins in CLAUDE.md

Sources: HomeOfVapourSynthEvolution GitHub releases

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: StuartCameronCode