Fix/dg 18 rotation metadata for videos is not applied serverside

[rafel-roboflow]

What does this PR do?

Resolves DG-18

Videos recorded on mobile devices in portrait mode were displaying incorrectly. The video dimensions showed as landscape (1920×1080) even though the video should appear as portrait (1080×1920). This happened because aiortc's MediaPlayer and PyAV don't automatically apply rotation metadata stored in the video's displaymatrix.

Solution
Detect rotation metadata using ffprobe (PyAV doesn't reliably expose displaymatrix side_data)
Apply rotation correction usin cv2.rotate() (which is fast for 90 deg rotations)

Type of Change

• Bug fix (non-breaking change that fixes an issue)

Testing

• [x ] I have tested this change locally
• I have added/updated tests for this change

I tested it with the same video provided by the user in DG-18.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in hard-to-understand areas
• My changes generate no new warnings or errors
• I have updated the documentation accordingly (if applicable)

Additional Context

---

Note

Corrects orientation of videos by reading rotation metadata and rotating frames during processing.

• Adds get_video_rotation, get_cv2_rotation_code, and rotate_video_frame in webrtc_worker/utils.py (uses ffmpeg-python and OpenCV)
• Extends VideoFrameProcessor.set_track(track, rotation_code=None) and applies rotation in _process_frame_async
• On video upload completion, probes file rotation and passes rotation_code to MediaPlayer/OnDemandVideoTrack setup in webrtc.py
• Improves logging around upload and rotation detection
• Updates requirements/_requirements.txt to include ffmpeg-python

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[grzegorz-roboflow]

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