Add video playback progress overlay

[kanihal]

Summary

• Add a bottom overlay progress bar for zoomed videos
• Show elapsed and total playback time when media duration is available
• Hide the progress overlay for streams/media without a finite duration
• Remove previously registered playback progress listeners before attaching replacements

Review follow-up

This supersedes #1790 and addresses the duplicate-listener and stale-closure issue raised in the review thread.

Validation

• node --check js/hoverzoom.js
• git diff --check origin/master...HEAD
• Targeted mocked-video regression check: calling addPlaybackProgress(video) twice leaves one current listener for each playback event and removes the stale callbacks

[gemini-code-assist]

Code Review

This pull request introduces a custom playback progress bar overlay for videos in HoverZoom, including CSS styling, time formatting, and event-driven progress updates. The reviewer recommends hiding this custom progress bar when the viewer is locked to avoid visual overlap with the browser's native video controls.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.

[kanihal]

Closing this replacement PR as requested. Both review fixes have been moved to the original PR #1790.