feat(navigation): provide grid keyboard navigation directives

[spliffone]

See #1345

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[gemini-code-assist]

Summary of Changes

Hello @spliffone, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a robust and flexible solution for keyboard navigation within grid-like structures in Angular applications. By leveraging a rectangle-based navigation service, it enables seamless keyboard interaction across diverse CSS layouts, including CSS Grid and Flexbox. The new directives provide comprehensive ARIA support and implement a roving tabindex pattern, significantly enhancing the accessibility of grid components.

Highlights

• Grid Keyboard Navigation: Introduces SiGridDirective and SiGridCellDirective to enable comprehensive keyboard navigation within grid layouts, adhering to WAI-ARIA grid patterns.
• Rectangle-Based Navigation Logic: Implements SiGridNavigationService which uses element bounding rectangles to determine cell relationships and navigate, making it compatible with any CSS layout (Grid, Flexbox, tables).
• Advanced Navigation Features: Supports arrow key navigation, Home/End for row/grid boundaries, and Page Up/Down for vertical jumps, with configurable wrapping modes ('nowrap', 'continuous', 'loop') and RTL support.
• Accessibility and Dynamic ARIA: Automatically manages ARIA attributes like role, tabindex, aria-disabled, aria-rowcount, aria-colcount, and dynamically derives row/column indices for cells in flat layouts.
• Roving Tabindex: Implements the roving tabindex pattern, ensuring only one navigable cell is in the tab sequence at a time for improved accessibility.

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[gemini-code-assist]

Code Review

This pull request introduces a new set of directives for creating accessible grids with keyboard navigation. The implementation is robust, leveraging rectangle-based positioning for layout independence, which is a great approach. The code is well-structured and uses modern Angular signals effectively. I've left a few comments with suggestions for minor improvements, mainly around code duplication, documentation accuracy, and improving maintainability by removing magic numbers. Overall, this is a solid contribution.

[github-actions]

Documentation.
Examples.
Playwright report.

Coverage Reports:

• element-ng
• element-translate-ng

[github-actions]