Support non-generic repositories

[uniquenode]

What problem are you trying to solve?

flate can't be used properly on projects using non-generic repositories.

Proposed solution

Repositories with a non-generic provider correctly work with flate when changing the provider to generic and providing credentials using --registry-config. There should be an option to treat non-generic repositories as generic and have it use --registry-config instead of failing. This way, non-generic repositories can be used without having to locally change and restore the source code before and after running flate.

Alternatives considered

No response

[buroa]

Reasonable ask. Today the provider check rejects any non-generic provider up front, before credential resolution, which is why switching to generic + --registry-config works.

Plan: add an opt-in override (e.g. --force-generic-provider) that routes non-generic OCIRepository/Bucket sources through the generic + --registry-config credential path instead of failing, so you don't have to edit and restore the source manifests around a run. Default (reject non-generic) stays as-is.