[Bug]: ScanAll always returns nil even when every scan operation fails

[Abhineshhh]

Version

sbi version: main @ d9404ec
Go: 1.26.5

What happened?

Pipeline.ScanAll logs per-repository and per-image errors but always returns nil. A total outage (registry down, Docker unavailable, all images failing) still reports success, and the CLI proceeds to generate reports from a stale database.

Nightly workflow uses if: success() before commit, so a fully failed scan can still look green and republish old recommendations.

Expected:

• Continue scanning remaining images on partial failure (current behavior).
• Return an error when all scan attempts fail (total outage).
• Log a clear summary when some attempts fail.

Steps to reproduce

1. Point config at unreachable registries, or stop Docker.
2. Run sbi scan --config-dir config --database test.db ....
3. Observe errors in logs but process exit code 0 and report generation continuing.