feat(build): ensure an image's BASE before BuildKit resolves it (charly#949) - #42

RegistryMirror)." So RegistryMirror was added to main by commits that moved the files. These are likely unrelated refactors/features. The mirror "closes the gap" incidentally. So it's not necessarily "#949 part 2" as a deliberate split. The body frames it as complementary. OK, no HC violation.

RegistryMirror), so the change was re-applied on a fresh branch off origin/main." So RegistryMirror was added to drive.go on main by some other PR. The body says "main now carries the other half it needed." So the mirror was added independently (perhaps as part of another feature or the #949 work).

undefined: baseImageRef" and ":30:15: c.ensureBaseImage undefined". Line 16 is in TestBaseImageRef, line 30 in TestEnsureBaseImage_NoOpForScratchAndEmpty. Plausible.

RegistryMirror)". So RegistryMirror was added to drive.go on main AFTER the branch was cut. So it's a separate change on main, not part of this PR. The body frames it as "the other half."

c.ensureBaseImage undefined