Add static code analysis to CI

.github/workflows/build.yml

@@ -25,6 +25,39 @@ jobs:
           pip install setuptools==69.5.1 wheel
           pip install -r requirements.txt
 
+      # Static analysis tools
+      - name: Install static analysis tools
+        if: runner.os == 'Linux'
+        run: |
+          pip install mypy==1.8.0
+          pip install flake8==7.0.0
+          pip install black==24.1.1
+
+      - name: Run static code analysis
+        if: runner.os == 'Linux'
+        run: |
+          # Critical checks
+          mypy_output=$(mypy lean/ \
+            --ignore-missing-imports \
+            --check-untyped-defs \
+            --show-error-codes \
+            --no-error-summary 2>&1 || true)
+
+          if echo "$mypy_output" | grep -q -E "Missing positional argument|\[call-arg\]"; then
+            echo "ERROR: Missing function arguments detected:"
+            echo ""
+            echo "$mypy_output" | grep -E "Missing positional argument|\[call-arg\]"
+            echo ""
+            echo "When adding/removing parameters from methods, ensure all call sites are updated."
+            exit 1
+          fi
+
+          flake8 lean/ --select=F821 --ignore=ALL
+
+          # Warning checks (don't fail the build)
+          flake8 lean/ --select=F401 --ignore=ALL --exit-zero
+          black --check lean/ --quiet || true
+
       - name: Run tests
         run: python -m pytest -s -rs