## Motivation and Context
This PR consolidates duplicated list-output formatting across the CLI
into shared rendering infrastructure.
Currently, each list command has its own copy of the same
json/quiet/table branching. This PR pulls that into shared rendering
infrastructure in `ContainerCommands`:
- `ListDisplayable` protocol for table + quiet output
- `renderJSON`, `renderTable`, `renderList` as pure functions that
return strings
- `emit()` as the single stdout boundary (no-ops on empty strings to
avoid blank-line regressions)
- `JSONOptions` so all JSON encoding goes through one path, including
volume inspect's pretty + ISO 8601 case
JSON encoding remains separate from display formatting: each command
still chooses its own JSON model, while `ListDisplayable` is used only
for table and quiet output. `ImageList` remains the intentional
exception for quiet mode so it can avoid unnecessary async work.
This change also replaces inline `JSONEncoder` usage with `renderJSON`,
removes the old `Codable+JSON.swift` helper, and moves `TableOutput` and
`ListFormat` into `ContainerCommands`. It also adds unit tests for the
shared rendering helpers and expands integration coverage for image,
network, and registry list formatting.
## Testing
- [x] Tested locally
- [x] Added/updated tests
- [ ] Added/updated docs
Raj