Module phi 

Phi Model V2 - Clean implementation using solid abstractions

This implements the Phi architecture (Phi-1, Phi-2, Phi-3) which includes:

• Microsoft Phi-1/1.5/2/3 models
• Uses unified Tensor type from tensor_core
• Implements Model trait from model_core

Structs

PhiAttention

Phi attention mechanism

PhiConfig

PhiLayer

Phi transformer layer

PhiMLP

Phi MLP (feed-forward network) - standard 2-layer MLP, not SwiGLU

PhiModelV2

Main Phi model implementation