Limit scan for log table with complex type will thrown exception.

### Search before asking

- [x] I searched in the [issues](https://github.com/apache/fluss/issues) and found nothing similar.

### Fluss version

0.9.0 (latest release)

### Please describe the bug 🐞

In org.apache.fluss.flink.sink.FlinkComplexTypeITCase#testComplexTypesInLogTable, change from `tEnv.executeSql("select * from complex_log_test").collect()` to `tEnv.executeSql("select * from complex_log_test limit 10").collect()` , exception will occurs:
```java
Caused by: java.lang.IndexOutOfBoundsException: index: 0, length: 1 (expected: range(0, 0))
at org.apache.fluss.shaded.arrow.org.apache.arrow.memory.ArrowBuf.checkIndexD(ArrowBuf.java:319)
at org.apache.fluss.shaded.arrow.org.apache.arrow.memory.ArrowBuf.chk(ArrowBuf.java:306)
at org.apache.fluss.shaded.arrow.org.apache.arrow.memory.ArrowBuf.getByte(ArrowBuf.java:508)
at org.apache.fluss.shaded.arrow.org.apache.arrow.vector.BaseFixedWidthVector.isSet(BaseFixedWidthVector.java:826)
at org.apache.fluss.shaded.arrow.org.apache.arrow.vector.BaseFixedWidthVector.isNull(BaseFixedWidthVector.java:815)
at org.apache.fluss.row.arrow.vectors.ArrowIntColumnVector.isNullAt(ArrowIntColumnVector.java:43)
at org.apache.fluss.row.columnar.ColumnarArray.isNullAt(ColumnarArray.java:55)
at org.apache.fluss.row.InternalArray.lambda$createElementGetter$530a4d25$1(InternalArray.java:157)
at org.apache.fluss.flink.utils.FlussRowToFlinkRowConverter.lambda$createInternalConverter$500d942e$1(FlussRowToFlinkRowConverter.java:164)
at org.apache.fluss.flink.utils.FlussRowToFlinkRowConverter.lambda$wrapIntoNullableInternalConverter$266ab4eb$1(FlussRowToFlinkRowConverter.java:94)
at org.apache.fluss.flink.utils.FlussRowToFlinkRowConverter.toFlinkRowData(FlussRowToFlinkRowConverter.java:75)
at org.apache.fluss.flink.utils.FlussRowToFlinkRowConverter.toFlinkRowData(FlussRowToFlinkRowConverter.java:67)
at org.apache.fluss.flink.utils.PushdownUtils.limitScan(PushdownUtils.java:325)
... 89 more

```

### Root Cause

`collectRows(batchScanner)` collects all `InternalRow` objects into a list first, then converts them to Flink rows in a separate loop. For Arrow format, these `InternalRow` objects are `ColumnarRow` backed by Arrow vectors:

- **Simple types** (int, string): `FieldGetter.getFieldOrNull()` copies the value — safe.
- **Complex types** (array, map, row): `getFieldOrNull()` returns a **lazy view** (`ColumnarArray`, `ColumnarMap`) that still references the underlying Arrow `FieldVector` buffers.

When `pollBatch()` transitions to the next batch, `VectorSchemaRoot.clear()` deallocates all Arrow buffers (capacity → 0). All previously collected `ColumnarArray` references now point to **empty buffers**, causing `IndexOutOfBoundsException: index: 0, length: 1 (expected: range(0, 0))`.

### Solution
Convert each row to Flink format **immediately during iteration** (before the batch transition clears the Arrow buffers). The `FlussRowToFlinkRowConverter.toFlinkRowData()` deep-copies all values (including array elements) into Flink's `GenericRowData`/`GenericArrayData`, so the resulting Flink objects are fully materialized and independent of Arrow buffers.

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start with FlinkComplexTypeITCase#testComplexTypesInLogTable and PushdownUtils.limitScan, then inspect collectRows(batchScanner) and FlussRowToFlinkRowConverter.toFlinkRowData(). Verify that complex values are converted before Arrow buffers are cleared between batches. The test should pass when selecting from complex_log_test with LIMIT 10 without an IndexOutOfBoundsException.

Written by the indexing model from the issue text.