Add "Skip to main content" link for keyboard navigation

[rak-phillip]

Is your feature request related to a problem? Please describe.

Users navigating with keyboards currently have to tab through all header navigation elements before reaching the main content area. This creates a poor experience for keyboard-only and screen reader users.

Describe the solution you'd like

Add a "Skip to main content" link that:

• Appears as the first focusable element on the page
• Is visually hidden by default but becomes visible when focused
• Jumps focus directly to the main content area when activated
• Follows WCAG 2.1 Level A accessibility guidelines

Acceptance Criteria

• Skip link is the first tabbable element on every page
• Link is visible when focused via keyboard
• Clicking/activating the link moves focus to main content
• Works correctly with screen readers

Additional context

• https://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-skip.html
• https://webaim.org/techniques/skipnav/#visible
• https://www.a11y-collective.com/blog/skip-to-main-content/