Adds focused unit tests for previously-uncovered cli helpers:
- TestAbsolutizePaths covers the path-vararg helper's empty,
absolute, and relative branches; complements the existing
TestAbsolutizeImageRegisterPaths.
- TestLastID is table-driven across nil/empty/sorted/unsorted/
duplicates/negative inputs.
- TestRunCheckMigrations* exercises every Compatibility branch
(compatible / migrations needed / incompatible / inspect
error) by stubbing bangerdExit and pointing the layout at a
temp-dir DB seeded directly with the schema_migrations table.
- TestNewBangerdCommandSubcommands pins the flag set against
accidental drift.
Lifts internal/cli coverage from 71% to 76% combined.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
