Add ChestXRaySegmentationTool for anatomical structure segmentation

Enables pixel-perfect segmentation of 14 anatomical structures:
- Left/Right Clavicle, Scapula, Lung, Hilus Pulmonis
- Heart, Aorta, Diaphragm, Mediastinum, Weasand, Spine

Features:
- Automatic segmentation of all organs
- Detailed metrics (area, centroid, bbox, size, intensity)
- Segmentation visualization overlays
- Uses TorchXRayVision PSPNet model

This completes MedRAX2 with 8 tools total:
1. NV-Reason-CXR - Clinical reasoning
2. MAIRA-2 Grounding - Phrase grounding with bboxes
3. CheXagent VQA - Interactive Q&A
4. Classification - Pathology detection
5. Report Generation - Radiology reports
6. Segmentation - Anatomical structure segmentation (NEW)
7. DICOM Processor - File handling
8. Web Browsing - Medical information

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app.py

@@ -93,6 +93,17 @@ if device == "cuda":
     except Exception as e:
         print(f"✗ Failed to load report generation tool: {e}")
 
+    try:
+        from medrax.tools.segmentation import ChestXRaySegmentationTool
+        segmentation_tool = ChestXRaySegmentationTool(
+            device=device,
+            temp_dir="temp"
+        )
+        tools.append(segmentation_tool)
+        print("✓ Loaded segmentation tool")
+    except Exception as e:
+        print(f"✗ Failed to load segmentation tool: {e}")
+
 # Load non-GPU tools
 try:
     from medrax.tools.dicom import DicomProcessorTool