fix: add missing huggingface_hub dependency and pin transformers version

[AjayBandiwaddar]

Problem

When installing dependencies fresh using pip install -r requirements.txt,
two issues occur:

1. huggingface_hub is not listed in requirements.txt but is a required
   dependency of transformers. This causes an ImportError on fresh installs.

2. transformers>=4.45.2 has no upper bound, which installs versions that
   conflict with huggingface_hub, breaking the application startup.

Fix

• Added huggingface_hub>=0.26.5 explicitly to requirements.txt
• Pinned transformers to <4.47.0 to prevent incompatible version installs

How to reproduce the bug

1. Clone the repo fresh
2. Run pip install -r requirements.txt
3. Run python main.py
4. See ImportError: cannot import name 'is_offline_mode' from 'huggingface_hub'

Testing

After this fix, python main.py starts successfully.

[AjayBandiwaddar]

Problem

When installing dependencies fresh using pip install -r requirements.txt, two issues occur:

1. huggingface_hub is not listed in requirements.txt but is a required
   dependency of transformers. This causes an ImportError on fresh installs.
2. transformers>=4.45.2 has no upper bound, which installs versions that
   conflict with huggingface_hub, breaking the application startup.

Fix

• Added huggingface_hub>=0.26.5 explicitly to requirements.txt
• Pinned transformers to <4.47.0 to prevent incompatible version installs

How to reproduce the bug

1. Clone the repo fresh
2. Run pip install -r requirements.txt
3. Run python main.py
4. See ImportError: cannot import name 'is_offline_mode' from 'huggingface_hub'

Testing

After this fix, python main.py starts successfully.

Note: This PR was developed with AI assistance (Claude). As per Sugar Labs contributing guidelines, I'm disclosing this. The AI helped me structure the fix, but I verified, and tested each change myself.