fix: correct package name, dependencies, and URL in setup.py

[haoyu-haoyu]

Summary

setup.py has three critical bugs that make the package completely uninstallable via pip install -e . or pip install .:

Bug 1: Wrong package name

# Before — looks for medgpt/ directory which doesn't exist
packages=['medgpt', 'medgpt.datasets', ...]

# After — matches the actual foresight/ directory
packages=['foresight', 'foresight.datasets', ...]

Bug 2: Missing comma causes string concatenation

# Before — Python concatenates into 'datasets==2.15.0transformers==4.35.2'
install_requires=[
    'datasets==2.15.0'      # <-- missing comma!
    'transformers==4.35.2',
]

# After
install_requires=[
    "datasets>=2.15",
    "transformers>=4.35",
]

Bug 3: URL points to old repository

# Before
url="https://github.com/w-is-h/medgpt"

# After
url="https://github.com/CogStack/Foresight"

Additional improvements

• Removed non-existent foresight.models sub-package (relates to no 'models' provided #1)
• Relaxed version pins (>= instead of ==) for compatibility
• Moved flash-attn to extras_require (requires CUDA build env)
• Added missing torch and numpy dependencies
• Added python_requires=">=3.9"

Test plan

git clone https://github.com/CogStack/Foresight.git
cd Foresight
pip install -e .     # Before: fails. After: succeeds
python -c "import foresight; print('OK')"

Partially addresses #1 (the foresight.models module is still missing from the repo, but at least setup.py no longer references it).