feat: Implement auto-hiding navbar with scroll detection

[riteshh-thakur]

Implements auto-hiding navbar functionality that provides users with more screen real estate while maintaining intuitive navigation access.

Problem
The navbar remained constantly visible, taking up valuable screen space and reducing content visibility during scrolling sessions.

Solution
Smart scroll detection: Hides navbar after scrolling down 100px, shows immediately on scroll up
Always visible near top: Navbar stays visible when scroll position < 10px
Smooth animations: 300ms CSS transform transitions without layout shifts
Fixed positioning: Consistent navbar placement across all pages
Proper scroll offsets: Anchored sections account for navbar height

Changes Made
New hook: useAutoHidingNavbar.ts for reusable scroll detection logic
Updated navbars: Both Home and Landing page navbars with auto-hide behavior
Layout fixes: Added scroll-mt-16 to anchored sections and pt-16 content padding
Transform animations: Smooth slide-up/down using CSS transforms

Files Modified
frontend/src/hooks/useAutoHidingNavbar.ts (new)
frontend/src/components/HomeComponents/Navbar/Navbar.tsx
frontend/src/components/LandingComponents/Navbar/Navbar.tsx
frontend/src/components/HomePage.tsx
frontend/src/components/LandingPage.tsx
frontend/src/components/LandingComponents/About/About.tsx
frontend/src/components/LandingComponents/Contact/Contact.tsx
frontend/src/components/LandingComponents/FAQ/FAQ.tsx
frontend/src/components/LandingComponents/HowItWorks/HowItWorks.tsx

Testing Instructions
Page load - Navbar should be visible at top
Scroll down - Navbar hides after 100px scroll
Scroll up - Navbar appears immediately
Anchor links - Content appears below navbar without overlap
Mobile viewport - Test responsive behavior
Rapid scrolling - Verify smooth animations

UX Benefits
64px additional content space when scrolling
Intuitive navigation access when needed
Smooth, jarring-free interactions
Better content focus during reading

[github-actions]

Thank you for opening this PR!

Before a maintainer takes a look, it would be really helpful if you could walk through your changes using GitHub's review tools.

Please take a moment to:

• Check the "Files changed" tab
• Leave comments on any lines for functions, comments, etc. that are important, non-obvious, or may need attention
• Clarify decisions you made or areas you might be unsure about and/or any future updates being considered.
• Finally, submit all the comments!

More information on how to conduct a self review:
https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/reviewing-proposed-changes-in-a-pull-request

This helps make the review process smoother and gives us a clearer understanding of your thought process.

Once you've added your self-review, we'll continue from our side. Thank you!