fix(install): switch update trace to dist-ref mode when source refs match

Composer's UpdateOperation::format renders the from/to versions through
DISPLAY_SOURCE_REF_IF_DEV first, but if both sides come out identical it
re-renders in DISPLAY_SOURCE_REF (when source refs differ) or
DISPLAY_DIST_REF (when only dist refs differ) so the trace doesn't show
a useless `pkg (X => X)` line. Mozart skipped the switch and emitted the
default form on both halves, so a same-version-different-dist-ref update
showed up as `dev-master def000 => dev-master def000` instead of
`dev-master def000 => dev-master`.

Add format_update_pretty_versions to render the pair Composer's way and
plumb the resolved to_full_pretty through PackageOperation::Update so
the trace recorder uses it verbatim.

Unblocks update_installed_reference and update_picks_up_change_of_vcs_type
installer fixtures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions