feat: create-pr option for timelapse workflow

[nberlette]

This PR adds an option to the Timelapse workflow for creating an auto-generated pull request for the newly generated timelapse video.

If the option is disabled, the video will just be uploaded as a workflow artifact with a retention period of 90 days. Otherwise, a new branch is created for the new file(s), and a simple PR with some of the video details is published using the GitHub CLI.

This also adds a debug log artifact step to the workflow, which captures the ffmpeg output to a temporary file and uploads it as a workflow artifact as well.

[nberlette]

LGTM 😛

[nberlette]

Alright, refactored the workflow and did a couple test runs. Seems to be performing pretty well.

The performance gains from using git's new(ish) sparse-checkout feature in combination with the cache action are tremendous. It just clocked in at a little over 8 minutes to generate a 17 minute video from 6 weeks of images. For reference, the scraper collects an average of ~115 images per day (5-6 per hour), equating to just about 5,000 images for the 6 week test period.

It's still absolutely horrendous in terms of DRY and code quality... And there is still a lot of room for further optimizations and improvements. But hey, it works 🤷🏼‍♂️

Still need to work out some logic for the scheduled trigger side of things. Until then, that feature will remain disabled and relegate this to manual workflow dispatches only.

SHIP IT