perf: remove redundant GSAP dependency, use Framer Motion exclusively

[snowrugar-beep]

Problem Statement

Both GSAP (35KB minified) and Framer Motion (45KB) are installed for animations. GSAP is only used in one component (CTA.tsx on the landing page) for scroll-triggered entrance animations. GSAP's ScrollTrigger plugin is registered and used for opacity/blur/y animations. These can be replicated with Framer Motion's useInView hook.

Evidence

• Frontend/package.json — Both gsap@3.15.0, @gsap/react@2.1.2, and framer-motion@12.40.0 are dependencies
• Frontend/src/components/landing/CTA.tsx — Uses useGSAP, gsap.from, ScrollTrigger for scroll-based entrance animations
• Framer Motion is used in Map.tsx and AddGistModal.tsx for spring animations and AnimatePresence

Impact

~35KB unnecessary bundle size for a single component's scroll animations. Dual animation paradigms confuse developers and increase maintenance burden.

Proposed Solution

1. Remove gsap and @gsap/react from dependencies
2. Refactor CTA.tsx to use Framer Motion's useInView and motion.div instead of GSAP ScrollTrigger
3. Remove gsap.registerPlugin(ScrollTrigger) call
4. Update all imports

Technical Requirements

• Visual behavior must be identical (opacity, blur, y offset animations on scroll)
• Stagger delay behavior must be preserved
• Scroll trigger timing must be equivalent

Acceptance Criteria

1. CTA section entrance animations work identically to current implementation
2. ScrollTrigger functionality (start: 'top 80%') preserved
3. gsap and @gsap/react removed from package.json
4. npm install succeeds without errors
5. npm run build succeeds
6. Bundle size decreases by ~35KB
7. All existing frontend pages render correctly

File Inventory

• Frontend/package.json
• Frontend/src/components/landing/CTA.tsx

Dependencies

None.

Testing Strategy

• Visual regression: verify CTA animations work in browser
• Build: verify bundle size decrease
• Manual: scroll to CTA, verify entrance animation triggers

Security Considerations

Removing a dependency reduces supply chain attack surface.

Definition of Done

• GSAP removed
• CTA refactored with Framer Motion
• Animations visually equivalent
• Build succeeds
• Bundle size decreased