fix: restructure src layout to proper package directory

Move src/__init__.py, detect.py, diagnose.py, extract_temp.py, utils/
into src/infrared_data/ to fix wheel package structure. Previously the
whl placed files at root instead of infrared_data/ directory, causing
ModuleNotFoundError on install.

Also update pyproject.toml packages.find config to use standard
src-layout discovery.

.gitignore

@@ -5,6 +5,7 @@ __pycache__/
 dist/
 build/
 *.egg
+*.whl
 
 # PyTorch
 *.pth