Fix GitHub workflow paths for new directory structure

- Update black check to use src/ tests/ main.py
- Add isort check for import sorting
- Update flake8 to check new paths
- Add ruff check for all Python versions
- Update mypy to check src/ directory
- Update pytest to run tests/ with src/ coverage
- Fixes workflow errors for all Python versions (3.8-3.11)

Author: Developer

.github/workflows/lint.yml

@@ -28,20 +28,28 @@ jobs:
 
     - name: Format check with black
       run: |
-        black --check main.py test_main.py
+        black --check src/ tests/ main.py
+
+    - name: Sort imports with isort
+      run: |
+        isort --check-only src/ tests/ main.py
 
     - name: Lint with flake8
       run: |
-        flake8 main.py test_main.py --count --select=E9,F63,F7,F82 --show-source --statistics
-        flake8 main.py test_main.py --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+        flake8 src/ tests/ main.py --count --select=E9,F63,F7,F82 --show-source --statistics
+        flake8 src/ tests/ main.py --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+
+    - name: Check with ruff
+      run: |
+        ruff check src/ tests/ main.py
 
     - name: Type check with mypy
       run: |
-        mypy main.py --ignore-missing-imports
+        mypy src/ --ignore-missing-imports
 
     - name: Run tests with pytest
       run: |
-        pytest --cov=. --cov-report=xml --cov-report=term-missing
+        pytest tests/ --cov=src --cov-report=xml --cov-report=term-missing
 
     - name: Upload coverage to Codecov
       uses: codecov/codecov-action@v3