fix: improve error verbosity in NEW_PULL and NEW_PUSH paths

[timmilesdw]

Summary

Enhanced error messages in NEW_PULL and NEW_PUSH implementations to provide the same level of detail as the old implementation. Errors now include contextual information like file paths, registry URLs, image tags, and digests.

Why do we need it, and what problem does it solve?

When NEW_PULL=1 is set, the d8 mirror pull command showed a generic error:

Error executing command: pull failed, see the log for details

Without NEW_PULL, the same command returned detailed errors:

Source registry is not accessible: HEAD https://registry.deckhouse.ru/v2/deckhouse/ee/manifests/lts: unexpected status code 401 Unauthorized

This made debugging authentication and network issues significantly harder with the new implementation.

Changes

• Critical fixes (5): Wrapped bare return err statements that lost all error context
• Error enhancements (16): Added file paths, registry URLs, tags, and digests to error messages
• Files modified (8): pull.go, push.go, modules.go, platform.go, puller.go, push.go, pusher.go, security.go

Why do we need it in the patch release (if we do)?

Not necessarily - this is an enhancement to error messages, not a critical bug fix.

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: deckhouse-cli
type: fix
summary: Improved error message verbosity in NEW_PULL and NEW_PUSH mirror operations