Add Keyboard Navigation for Section Jumping

[bae080311]

Summary

Improve accessibility by allowing users to navigate between sections using keyboard shortcuts (e.g., PgUp, PgDown, or custom keys). This provides an alternative to mouse/trackpad scrolling and benefits users who rely on keyboard navigation.

Proposed Solution

Implement a global event listener for keyboard events within the ScrollManager. Map specific keys (configurable via options) to trigger jump-section's programmatic scroll to the next/previous section. Ensure focus management is considered.

Acceptance Criteria

• Users can navigate to the next and previous sections using configurable keyboard shortcuts.
• The scroll animation for keyboard navigation is smooth.
• Focus is appropriately managed after jumping to a new section.
• Documentation includes details on enabling and configuring keyboard navigation.

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