Feat/cityscapes tutorial

[tejasstanley]

Summary

This draft PR adds a tutorial notebook for running semantic segmentation evaluation on the Cityscapes dataset with PerceptionMetrics.

Changes

• Added examples/tutorial_cityscapes_image_segmentation.ipynb
• Demonstrates evaluation with a pretrained SegFormer model fine-tuned on Cityscapes
• Shows how to create the model configuration from the Hugging Face image processor
• Shows how to load Cityscapes validation data, run predictions, visualize results, and compute segmentation metrics
• Updated Cityscapes dataset support for the tutorial workflow
• Updated torch segmentation inference to handle models that return logits outputs and resize logits back to the input resolution

Status

• Tutorial notebook added
• Prediction workflow tested
• Evaluation workflow tested on the Cityscapes validation split

Reference Issue #579