## What this PR does
Makes `topics[].config` optional across the Kafka typed API, generated
schema, documentation, and chart contract. The KafkaTopic template
already omits an empty config, and Strimzi accepts the field as
optional; the Cozystack schema was the layer incorrectly rejecting such
topics.
The Helm test renders a topic without config and asserts `spec.config`
is absent. The Chainsaw fixture also omits config and waits for the
resulting KafkaTopic to reach Ready.
Go API compatibility: `Topic.Config` changes from `runtime.RawExtension`
to `*runtime.RawExtension`, so Go callers constructing that field must
pass a pointer. The Terraform provider intentionally does not model
Kafka topic tuning (`config`), so this does not require a provider
follow-up.
Validation:
- `helm unittest packages/apps/kafka`: 36/36 passed.
- `go vet ./kafka` in `api/apps/v1alpha1`: clean; the package has no
test files, so this shows it compiles.
- root `make generate`, which owns `zz_generated.deepcopy.go`, and `make
-C packages/apps/kafka generate`: no diff.
### Screenshots
Not a UI change.
### Downstream repositories
Walked the trigger map against all nine changed files. The provider's
Kafka model deliberately excludes `topics[].config`; no downstream
repository mirrors this nested field or its requiredness.
- [x] No downstream repository is affected by this change
- [ ] [cozystack/website](https://github.com/cozystack/website) -
follow-up:
- [ ]
[cozystack/terraform-provider-cozystack](https://github.com/cozystack/terraform-provider-cozystack)
- follow-up:
- [ ]
[cozystack/ansible-cozystack](https://github.com/cozystack/ansible-cozystack)
- follow-up:
- [ ] [cozystack/ccp](https://github.com/cozystack/ccp) - follow-up:
- [ ] [cozystack/talm](https://github.com/cozystack/talm) - follow-up:
- [ ] [cozystack/cozyhr](https://github.com/cozystack/cozyhr) -
follow-up:
- [ ] [cozystack/cozy-proxy](https://github.com/cozystack/cozy-proxy) -
follow-up:
- [ ]
[cozystack/cozystack-telemetry-server](https://github.com/cozystack/cozystack-telemetry-server)
- follow-up:
- [ ]
[cozystack/external-apps-example](https://github.com/cozystack/external-apps-example)
- follow-up:
- [ ] [cozystack/examples](https://github.com/cozystack/examples) -
follow-up:
### Release note
```release-note
fix(kafka): allow topics to omit the optional Strimzi config map
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **New Features**
- Kafka topic configuration is now optional. Topics can be created
without explicitly providing configuration settings.
- Topic configuration is omitted from serialized resources when not
specified.
- **Bug Fixes**
- Improved handling of topic resources without configuration, including
correct readiness validation and rendering.
- **Documentation**
- Updated Kafka configuration documentation and schemas to reflect that
topic configuration is optional.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Aleksei Sviridkin
ee09e73343