[Docs][Core] Add Javadoc to TaskExecutionService inner classes (cooperative/blocking execution model)

Sub-issue of #10533

Scope

TaskExecutionService implements Zeta's dual-mode task execution: cooperative (work-stealing) for lightweight tasks and blocking (dedicated thread) for I/O-heavy tasks. Its inner classes — CooperativeTaskWorker, RunBusWorkSupplier, BlockingWorker, and TaskGroupExecutionTracker — implement this model but are entirely undocumented.

File

seatunnel-engine/seatunnel-engine-server/src/main/java/org/apache/seatunnel/engine/server/TaskExecutionService.java

Methods to document

Class / Method	Line	What to explain
submitThreadShareTask(...)	210	Routes cooperative (non-blocking) tasks into the shared work-stealing queue
submitBlockingTask(...)	235	Launches a dedicated thread per blocking task; why blocking tasks must not share threads
deployTask(TaskGroupImmutableInformation)	276	Deserializes task group; loads connector classes; starts thread-share or blocking tasks based on task type
notifyTaskStatusToMaster(...)	442	Reports per-task status changes to CoordinatorService via Hazelcast operation
CooperativeTaskWorker (class)	731	Work-stealing cooperative executor; exclusiveTaskTracker for single-task phases; loop structure
CooperativeTaskWorker.run()	753	Task-stealing loop; transitions between exclusive and shared task execution; yield on empty queue
RunBusWorkSupplier.runNewBusWork(boolean)	849	Creates new CooperativeTaskWorker threads on demand when queue pressure is detected
BlockingWorker.run()	667	Dedicated-thread lifecycle: init → call → done; status notification on completion or exception
TaskGroupExecutionTracker.taskDone(Task)	928	All-tasks-complete detection (countdown latch pattern); triggers group-level completion and resource cleanup
TaskGroupExecutionTracker.exception(Throwable)	901	First-exception-wins: records the first failure and cancels all sibling tasks in the group

How to contribute

1. Fork the repo and create a branch
2. Add Javadoc to the methods above
3. Run ./mvnw spotless:apply and ./mvnw -q -DskipTests verify
4. Open a PR with title: [Docs][Core] Add Javadoc to TaskExecutionService inner classes