[kafka] Handle basic Produce requests independently of storage

### Purpose

Part of #4185. PR05 of the Kafka compatibility sequence.

Implement non-idempotent Produce v3-v11 with a narrow backend contract. Validate acknowledgements, topic/partition identities and record batches; isolate invalid partitions, preserve response order and copy record data independently of the network buffer.

### Acceptance criteria

- [ ] Valid requests preserve records, headers, listener context, acks and timeout.
- [ ] Invalid batches and topics do not suppress valid partitions in the same request.
- [ ] Transactional/idempotent/control batches and duplicate partition entries are rejected.
- [ ] acks=0 emits no response and releases the request buffer on success and failure.
- [ ] Production ApiVersions continues to expose only the existing capabilities until append is integrated.

### Dependencies

PR04 Metadata (#4261 / #4266).

### Scope boundary

No row conversion, gateway append or production Produce registration.

### Implementation

Draft PR #4284: https://github.com/apache/fluss/pull/4284

Java 11 validation: 69 unit tests and 2 integration tests passed at `936fd3f39e9e6fe595ed6bf8e30f0e2b5185ffe3`. Review and merge remain pending.

Start by reviewing draft PR #4284 and the Metadata dependency in #4261/#4266, then inspect the stated Java 11 validation results. Done means the acceptance criteria hold for Produce v3-v11 while storage conversion, gateway append, and production registration remain out of scope.

Written by the indexing model from the issue text.