UI: Add interactive Backgrounds

[rhyanvargas]

• Hero: https://www.shadcn.io/background/beams
• Button CTA: https://www.shadcn.io/background/gradient
• About: https://www.shadcn.io/background/particles
• Featured Project Card under CTA: https://www.shadcn.io/background/sparkles
• Other Projects Card (variant: "gradient-bg"): https://www.shadcn.io/background/gradient-animation
• Footer: https://www.shadcn.io/background/beams-with-collision

Other

• https://www.shadcn.io/background/hexagon
• https://www.shadcn.io/background/interactive-grid-pattern