feat(landing): add mobile app showcase, user journey, and app store download CTAs (#55)

[SparshGarg999]

Fixes #55

What & Why

The current landing page primarily highlighted desktop task discovery, but lacked visibility for the Gibwork mobile application and the step-by-step user earning journey. This PR integrates a dedicated Mobile App Showcase and a 4-step User Journey section to improve conversion, highlight mobile-specific features, and provide direct App Store and Google Play download links.

Changes

• Updated Hero Section: Refined hero copy to emphasize cross-platform earning ("Find opportunities, complete tasks, and earn rewards seamlessly across web and mobile.") and added iOS & Android app CTA buttons.
• Added UserJourney Component: Implemented a responsive 4-step sequence (Create Profile -> Find Opportunities -> Complete Work -> Get Rewarded) with icons and hover animations.
• Added MobileShowcase Component: Added a native mobile device preview card featuring live bounty status cards, real-time earnings notifications, and verified store badges (Apple App Store & Google Play).
• Updated siteConfig: Added verified direct links for App Store (id6757281508) and Google Play (com.gibwork.app).

How This Was Tested

Check	Command	Outcome
Next.js production build	npm run build	Pass (5/5 static pages prerendered)
Type check & lint	next build	Pass (0 errors)
Responsive layout	Mobile / tablet / desktop viewport validation	Pass

Scope & Risks

• Breaking changes: None. Pure additive UI enhancement using existing Tailwind and Framer Motion tokens.

[vercel]

@SparshGarg999 is attempting to deploy a commit to the gibwork Team on Vercel.

A member of the Team first needs to authorize it.