fjj v0.2.3

Restores discovery of existing jj identity configuration on macOS, including
~/Library/Application Support/jj/config.toml and conf.d/*.toml. These locations
were no longer read after embedding jj 0.37, leaving user.name and user.email
unset for users of older jj configurations.

The fix applies to both fjj and fjjui. It preserves older jj's config precedence,
honors JJ_CONFIG and normal identity overrides, and reads configuration entirely
in-process under the existing kernel policy. Existing commit authors are unchanged.

Includes native Linux and macOS binaries for x86_64 and ARM64. Every target is
tested for config discovery, commit identity, Git/SSH workflows, and embedded UI
operation before publication. Each archive includes both executables and source
provenance; adjacent SHA-256 files verify the downloads.

Published from the successful four-platform release build
using the verified-artifact publisher.