feat(video): build reusable LMS video player component

[philipcocu1-cyber]

Summary

Introduces a reusable LMS video player component that serves as the foundation for video-based learning across Gathera. The component is designed to be reusable for courses, conference recordings, sessions, and other video content while providing an accessible and responsive playback experience.

Changes Made

• Created a reusable video player component that accepts a video URL as a prop
• Added play and pause controls
• Implemented a seek/progress bar
• Added volume adjustment and mute/unmute functionality
• Implemented fullscreen support
• Added playback speed controls
• Displayed current playback time and total duration
• Included loading and error states for improved user experience
• Implemented responsive layouts for desktop, tablet, and mobile devices
• Added keyboard accessibility for common playback actions
• Handled invalid or unavailable video URLs gracefully

Acceptance Criteria

• ✅ Works across desktop, tablet, and mobile devices
• ✅ Accepts a video URL via props
• ✅ Reusable across courses, sessions, and conference content
• ✅ Gracefully handles invalid or unavailable video URLs

Closes #627