fix: add ruff configuration and fix CI workflow

pyproject.toml

@@ -81,3 +81,20 @@ skip = [".venv", "venv"]
 max-line-length = 100
 exclude = [".venv", "venv", "build", "dist"]
 per-file-ignores = ["__init__.py: F401"]
+
+[tool.ruff]
+target-version = "py39"
+line-length = 100
+
+[tool.ruff.lint]
+select = ["E", "F", "W", "C90", "I"]
+ignore = [
+    "E501",  # line too long - handled by black
+    "F401",  # unused imports - common in __init__.py files
+    "F841",  # local variable is assigned but never used
+    "C901",  # function too complex
+]
+
+[tool.ruff.lint.per-file-ignores]
+"__init__.py" = ["F401"]  # Allow unused imports in __init__.py
+"tests/*" = ["F401"]  # Allow unused imports in tests