fix(cli): handle targets and registries in list

[chaz8081]

Summary

• wire positive-vibes list to actually handle targets and registries resource types instead of silently returning no output
• add dedicated list render functions for targets and registries with JSON parity
• update list command help text/examples so advertised resource types match real behavior
• add regression tests that assert list targets and list registries produce visible output

Test Plan

• go test ./internal/cli -run 'ListCmd_(TargetsProducesOutput|RegistriesProducesOutput)' -v
• go test ./internal/cli -v
• go test ./...