style(hero-abacus): add purple bead colors for dark theme

Previously only styled column posts and reckoning bar, leaving
bright default bead colors that clashed with dark background.

Added:
- Heaven beads: light purple rgba(196, 181, 253, 0.8)
- Earth beads: medium purple rgba(167, 139, 250, 0.7)
- Both with violet strokes for definition

Beads now blend harmoniously with the dark purple gradient background.

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

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

apps/web/src/components/HeroAbacus.tsx

@@ -22,6 +22,16 @@ export function HeroAbacus() {
       stroke: 'rgba(255, 255, 255, 0.25)',
       strokeWidth: 3,
     },
+    heavenBeads: {
+      fill: 'rgba(196, 181, 253, 0.8)',
+      stroke: 'rgba(167, 139, 250, 0.9)',
+      strokeWidth: 2,
+    },
+    earthBeads: {
+      fill: 'rgba(167, 139, 250, 0.7)',
+      stroke: 'rgba(139, 92, 246, 0.9)',
+      strokeWidth: 2,
+    },
   }
 
   // Detect when hero scrolls out of view