feat(backgrounds): add constellation background

src/locales/en.json

@@ -1163,6 +1163,8 @@
       "matrixRainDesc": "Falling columns of glyphs",
       "liquidGradient": "Liquid Gradient",
       "liquidGradientDesc": "Blurred mesh gradient blobs",
+      "constellation": "Constellation",
+      "constellationDesc": "Particles linked by lines",
       "geminiEffect": "Gemini Effect",
       "geminiEffectDesc": "SVG effect like Google Gemini",
       "speed": "Speed",
@@ -1186,6 +1188,7 @@
       "lineColor": "Line Color",
       "wind": "Wind",
       "charset": "Charset",
+      "linkDistance": "Link Distance",
       "bgColor": "Background Color",
       "fillColor": "Fill Color",
       "color1": "Color 1",