feat: add graphThemes for heatmap visualization with optimized color schemes

Author: pphatdev

src/utils/themes/graph.ts

@@ -0,0 +1,89 @@
+import { Theme } from '../../types.js';
+
+/**
+ * Graph-optimized themes for the /graph activity heatmap.
+ *
+ * These themes are tuned so that `iconColor` (the heatmap cell fill) is vivid
+ * and high-contrast against the near-black `bgColor`, making contribution
+ * density immediately readable.
+ *
+ * Key colour roles in the graph:
+ *   titleColor  → large heading text (username + year)
+ *   textColor   → subtitle, month labels, legend labels
+ *   iconColor   → heatmap cell fill (levels 1-4 derived from this)
+ *   bgColor     → canvas background (should be very dark)
+ *   borderColor → background grid lines and divider
+ */
+export const graphThemes: { [key: string]: Theme } = {
+    /** Emerald green — Northern Lights feel */
+    aurora: {
+        titleColor: '#a8ffce',
+        textColor: '#c8ffd4',
+        iconColor: '#00e676',
+        bgColor: '#020c12',
+        borderColor: '#0a3026',
+    },
+
+    /** Pure terminal green on black — classic hacker aesthetic */
+    matrix: {
+        titleColor: '#00ff41',
+        textColor: '#39ff14',
+        iconColor: '#00cc33',
+        bgColor: '#000000',
+        borderColor: '#003300',
+    },
+
+    /** Red-orange fire gradient — heat/intensity */
+    inferno: {
+        titleColor: '#ff9a00',
+        textColor: '#ffcf77',
+        iconColor: '#ff4500',
+        bgColor: '#0d0200',
+        borderColor: '#3d0a00',
+    },
+
+    /** Deep cyan-blue water — calm and readable */
+    ocean: {
+        titleColor: '#00d4ff',
+        textColor: '#b2f0ff',
+        iconColor: '#0099cc',
+        bgColor: '#020d1a',
+        borderColor: '#0a2a40',
+    },
+
+    /** Magenta / purple — cyberpunk neon */
+    neon: {
+        titleColor: '#ff00cc',
+        textColor: '#ff99ee',
+        iconColor: '#cc00ff',
+        bgColor: '#0a000f',
+        borderColor: '#3d0050',
+    },
+
+    /** Amber / gold — warm solar glow */
+    solar: {
+        titleColor: '#ffd700',
+        textColor: '#ffe88a',
+        iconColor: '#f5a623',
+        bgColor: '#0d0900',
+        borderColor: '#3a2800',
+    },
+
+    /** Violet / purple — deep-space galaxy */
+    galaxy: {
+        titleColor: '#c084fc',
+        textColor: '#e9d5ff',
+        iconColor: '#8b5cf6',
+        bgColor: '#05020f',
+        borderColor: '#1e0a40',
+    },
+
+    /** GitHub native dark palette — green contribution cells */
+    'github-dark': {
+        titleColor: '#58a6ff',
+        textColor: '#c9d1d9',
+        iconColor: '#39d353',
+        bgColor: '#0d1117',
+        borderColor: '#21262d',
+    },
+};