This fixes a regression in 1.1.1/1.1.2 where our PACKAGING docs mention
using `fetch-zig-cache.sh` but it was removed. This commit adds it back,
generating its contents from the build.zig.zon file (via zon2nix which
we use for our Nix packaging).
For packagers, there are no dependency changes: you still need Zig and
POSIX sh. For release time, Ghostty has a new dependency on `jq` but
otherwise the release process is the same. The check-zig-cache.sh script
is updated to generate the new build.zig.zon.txt file.
It seems like the raw data version of the kitty graphics transmit
operation is meant to be unassociated (aka straight) alpha, though I
can't find any definitive documentation either way- but in any case
unassociated alpha is more common in image formats and makes the
handling easier for the rest of it.
Also removed a redundant call to `decode_frame_config`, since it's
called implicitly when we call `decode_frame` right after.
- move wuffs code from src/ to pkg/
- eliminate stray debug logs
- make logs a warning instead of an error
- remove initialization of some structs to zero
