Add CTRL contrib model port

[dhwanw]

Description

Adds NeuronX port of Salesforce CTRL to the contrib models collection.

Model Information

Field	Value
Model	Salesforce/ctrl
Architecture	Decoder-only transformer (conditional text generation)
Parameters	1.63B
TP Degree	1
Precision	BF16

Checklist

• Model compiles successfully on Neuron
• Token matching validated (99.06% greedy, 99.84% teacher-forced)
• Performance profiled (59.3 tok/s)
• README with architecture details, usage, validation results
• Integration tests included

Folder Structure

contrib/models/ctrl/
├── README.md
├── src/
│   ├── __init__.py
│   └── modeling_ctrl.py
└── test/
    └── integration/
        └── test_model.py

Testing

• Token Match (greedy): 99.06% (634/640 tokens)
• Token Match (teacher-forced): 99.84%
• Throughput: 59.3 tok/s (TP=1, BS=1, seq_len=128)

Compatibility

• Neuron SDK: 2.22+
• Instance: trn1.32xlarge

🤖 Generated with Claude Code