feat(fourier): add dog head preset

Build the dog outline from one mirrored right half.
Smooth it with Chaikin corner cutting (3 passes).
Also add a ROADMAP note for the circles slider thumb.

src/assets/i18n/en.json

@@ -679,6 +679,7 @@
     "PRESET_HEART": "Heart",
     "PRESET_STAR": "Star",
     "PRESET_SQUARE": "Square",
+    "PRESET_DOG": "Dog",
     "CIRCLES": "Circles",
     "SPEED": "Speed",
     "SHOW_CIRCLES": "Show circles",