[BUG] INT96 Parquet timestamp decoding silently produces wrong values outside int64 range

**Describe the bug**
When reading Parquet files with INT96 timestamps, cuDF silently produces incorrect values for timestamps outside the representable range of the requested output type.

**Steps/Code to reproduce bug**
[TestCudfInt96.java](https://gist.github.com/piotrrzysko/700d361a8ed334112418bb32163c488b) demonstrates two scenarios in which the bug occurs.

**Expected behavior**
cuDF should be able to read the full INT96 range without silent data corruption

**Environment overview (please complete the following information)**
- Environment location: Cloud (AWS)
- Method of cuDF install: Maven dependency (`ai.rapids:cudf:26.06.0-cuda13`)