[bug]: registry lookup by name can silently fail and delete may use ID 0

[PrasunaEnumarthy]

Description

GetRegistryIdByName() can fail silently in two ways:

It returns (0, nil) when the registry name is not found.
It calls ListRegistries() without a query filter, so lookup depends on paginated results and may miss registries beyond the first page.

This becomes user-visible in harbor registry delete <registry-name> because the command ignores lookup errors and may attempt to delete registry ID 0.

Steps to Reproduce

1. Ensure multiple registries exist (enough to trigger pagination)
2. Run command:
   harbor registry delete
3. Observe error

• Lookup may silently fail
• Delete may proceed with registry ID 0

Expected Behavior

• Lookup should use exact-name filtering via query
• Missing registry should return:
  registry '' not found
• Delete command should stop immediately if lookup fails

Actual Behavior

• Lookup returns (0, nil) when registry is not found
• Pagination may cause valid registries to be missed
• Delete command may proceed using ID 0

Environment

• OS: (e.g., Linux / macOS / Windows)
• Tool version: (e.g., Harbor CLI version)
• Other relevant details: N/A

Additional Context

Affected files:

• pkg/api/registry_handler.go
• cmd/harbor/root/registry/delete.go
  Similar issue fixed for users in PR fix(user): resolve missing id parsing and pagination in user executio… #820