feat: Video upload and inline video player in chat messages

[rdwj]

Summary

Support video file uploads and display video content inline in the conversation. Users can share video for analysis, and agents can reference specific frames or segments in their responses.

UX Requirements

• Video file upload via file picker or drag-and-drop
• Upload progress bar for large video files with cancel option
• Inline video player in messages (HTML5 video element with native controls)
• Video thumbnail preview in the input area before sending
• Duration and file size display on the attachment chip
• Format validation with clear error messages for unsupported types
• Processing status indicator while server-side analysis is in progress
• Responsive player sizing — fit message width without overflow

Implementation Notes

Upload video files via the /v1/files endpoint (same as general file upload). Server-side processing (frame extraction, transcription) happens asynchronously — poll or subscribe for completion. Display a skeleton/spinner state in the message while processing. The video player should use native HTML5 <video> controls for consistency and accessibility. Consider lazy-loading video elements in long conversations to preserve performance.

Companion Issues

Companion issues filed on fips-agents/agent-template, fips-agents/gateway-template, fips-agents/fips-agents-cli, and fips-agents/examples.

Size

M