Fix opengraph preview image location

[TimMonko]

🧰 Task

Currently, the opengraph preview is only correctly finding the image (which can be found at ./{ver}/_static/opengraph_image.png) on some random pages... by pointing the metadata to ../dev/.... It makes no sense to me

The image does live at both stable and dev

If we could just shove the image into /_static/opengraph_image.png it should work, but I'm probably doing something wrong in the setup, not sure

1. stable/plugins points to _static
2. stable/community points to ../dev/_static
3. dev/community points to _static though....
4. napari.org/stable points to ../dev/_static ........

[psobolewskiPhD]

So the images is actually located here:
https://github.com/napari/napari.github.io/tree/gh-pages/dev/_static
in dev/_static
because we always deploy to dev (or a version folder):

docs/.github/workflows/build_and_deploy.yml

Line 116 in 24d5939

destination_dir: ${{ github.event.inputs.target_directory || 'dev' }}

All the stuff int he root of the pages repo is from before versioning and is stale (we could remove it IMO since it's redirected anyways). So to fix the stable we should just put the image in root/_static on GitHub pages. This is not "correct" but it will fix the deployed pages with minimal fuss.
And then in this repo, I think we should change the link to use /dev/_static and everything will work going forward.

I'm not sure about where the .. came from, I assume it's related to the copy of the docs.

[psobolewskiPhD]

OK here is the ..
it's being used to fix unversioned pages exactly for this sort of thing:
https://github.com/napari/napari.github.io/blob/0c0ec08d48a280fd66bc6d10227a1b4a40df3124/.github/workflows/unversioned_pages.yml#L37-L42

[TimMonko]

After napari/napari.github.io#424 the preview is looking good for all instances.

Still unsure about #700, I think it makes sense in that we would correctly update the preview image in docs rather than on the gh-pages branch, but want others opinion.