fix: DrillOrbit fades in/out at path edges, DrillBitSpinner uses radial mask instead of hard clip

Former-commit-id: 3aea27f3e17984634206ca817d074b18e712933e

components/blocks/ReferencesSlider.tsx

@@ -7,6 +7,7 @@ import Image from 'next/image';
 import { HoverShineOverlay } from '@/components/ui/HoverShineOverlay';
 import { DrillOrbit } from '@/components/ui/decorations/DrillOrbit';
 import { DrillBitSpinner } from '@/components/ui/decorations/DrillBitSpinner';
+import { DrillTeeth } from '@/components/ui/decorations/DrillTeeth';
 
 export interface Reference {
   id: string;
@@ -83,7 +84,7 @@ export function ReferencesSlider(props: ReferencesSliderProps) {
   };
 
   return (
-    <section className="py-24 bg-neutral-dark text-white overflow-hidden relative select-none">
+    <section className="py-24 bg-neutral-dark text-white relative overflow-hidden">
       <div className="absolute inset-0 bg-gradient-to-b from-neutral-dark via-neutral-900 to-neutral-dark z-0" />
       
       <div className="container relative z-10 mb-12 flex flex-col md:flex-row justify-between items-end gap-6">
@@ -159,6 +160,8 @@ export function ReferencesSlider(props: ReferencesSliderProps) {
       </div>
       {/* Decorative: abstract HDD bore trajectory */}
       <DrillOrbit side="left" />
+      {/* Organic wave divider */}
+      <DrillTeeth position="bottom" fill="var(--color-neutral-dark)" />
     </section>
   );
 }