`canact.svg` is the mark. PNG and other rasters are generated from it.
```bash
make brand
```
That writes `/tmp/canact-brand/org-avatar-1024.png` and
`/tmp/canact-brand/social-preview.png` (the painted mark is
scaled to 600px tall on the 1280x640 banner, not the padded
512 square). Do not commit those files.
GitHub org avatar and repo social preview are uploaded from the
generated PNG. Edit the SVG, then re-run `make brand`.