fix: add missing color-palette parameter to generate-flashcards function

- Add color-palette parameter to generate-flashcards function signature
- Fixes "unexpected argument: color-palette" Typst compilation error
- Maintains backward compatibility with default palette
- Enables all color palette options (default, colorblind, mnemonic, grayscale, nature)
- Now supports: python3 src/generate.py --color-palette colorblind --color-scheme place-value

🤖 Generated with [Claude Code](https://claude.ai/code)

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

templates/flashcards.typ

@@ -385,6 +385,7 @@
   hide-inactive-beads: false,
   bead-shape: "diamond",
   color-scheme: "monochrome",
+  color-palette: "default",
   colored-numerals: false,
   scale-factor: 0.9  // Manual scale adjustment (0.1 to 1.0)
 ) = {