Java-SDK OpenLineage support (lineage callback from Java task to Python supervisor)

### Background In the AIP-108 dev@ thread ([2026-05-13 reply][maciej-reply]), Maciej Obuchowski outlined what OpenLineage needs from the Java SDK: - **Generic task lifecycle events** — when OL is enabled, every task execution emits OL start / complete / failure events via the listener framework, driven by the Python task runner. For Java tasks, the listener calls still fire from the Python side around the Java subprocess (e.g. near `on_task_instance_running` / `on_task_instance_success` in `task-sdk/src/airflow/sdk/execution_time/task_runner.py:1196` and `:1921`). No code change is required to keep this working for the "task ran, task succeeded" signal. - **Operator/hook-specific lineage data** — the part that currently relies on Python operators/hooks being in-process and reading state from the `TaskInstance` after `execute()`. This does **not** work for a Java task because the user code runs in a JVM subprocess that the Python listener cannot introspect. Maciej's conclusion: v1 of the Java SDK does not need OL emission from inside the Java task, but the IPC and Java-side API must **not block** a future lineage interface from being added. Concretely: > "able to send serialized data back from the task execution to Python; > and an API in the Java SDK for users to be able to specify that data." ### What needs to happen 1. **Reserve a lineage channel on the coordinator IPC.** When the Java subprocess returns task results to the supervisor, the protocol should allow an optional serialized lineage payload alongside the existing result message. The base `BaseCoordinator` interface needs to expose a hook the supervisor calls with that payload (no-op by default). 2. **Expose a Java SDK API for users to declare lineage data.** Minimal shape, mirroring how Python tasks can attach lineage to a `TaskInstance` today. Exact API to be decided once the IPC channel exists, but it should be: - opt-in (no overhead for tasks that don't use…