feat: MFM Sparkle animation (#7813)

* Add sparkle mfm animation ✨

* Cleanup sparkle effect

+ spaces -> tabs and other codestyle
+ use proper image
+ listen for resizes
+ use font-size to determine particle size (for fun with x2/3/4 stacking)

locales/en-US.yml

@@ -899,6 +899,8 @@ _mfm:
   fontDescription: "Sets the font to display contents in."
   rainbow: "Rainbow"
   rainbowDescription: "Makes the content appear in rainbow colors."
+  sparkle: "Sparkle"
+  sparkleDescription: "Infuses a sparkling animation"
 _reversi:
   reversi: "Reversi"
   gameSettings: "Game settings"