feat: add --tag alias, improve tags output, add management commands

- add --tag alias for --digest in vulns, scan, info, sbom commands
- tags command now shows digest column for each tag
- add delete-repo, delete-project, purge, clean-all commands
- add config command for project settings
- bump version to 0.3.0

PROJECT.md

@@ -48,3 +48,7 @@ Command-line interface for managing Harbor container registry. Provides quick ac
 - Harbor instance is accessible over HTTPS
 - User has appropriate permissions for requested operations
 - Credentials file follows established format when present
+
+## References
+
+- Harbor API docs: `~/git/harbor/docs`