test: add quality-depth gates and mature CPU coverage

pyproject.toml

@@ -45,6 +45,7 @@ dependencies = [
 [project.optional-dependencies]
 dev = [
     "build==1.2.2.post1",
+    "hypothesis==6.165.3",
     "mypy==1.13.0",
     "pytest==9.1.1",
     "pytest-cov==7.1.0",
@@ -58,6 +59,9 @@ ci = [
     "pip-licenses==5.5.5",
     "twine==7.0.0",
 ]
+quality = [
+    "mutmut==3.7.0",
+]
 
 [project.scripts]
 obliteratus = "obliteratus.cli:main"
@@ -104,6 +108,21 @@ markers = [
     "remote: tests that require a remote execution provider or credentials",
 ]
 
+[tool.mutmut]
+source_paths = ["obliteratus/", "scripts/"]
+only_mutate = [
+    "obliteratus/config.py",
+    "scripts/check_coverage_thresholds.py",
+]
+pytest_add_cli_args = ["--no-cov", "-q"]
+pytest_add_cli_args_test_selection = [
+    "tests/test_config.py",
+    "tests/test_config_properties.py",
+    "tests/test_coverage_thresholds.py",
+]
+mutate_only_covered_lines = true
+on_dependency_change = "rerun"
+
 [tool.uv]
 constraint-dependencies = ["pillow>=12.2.0"]
 exclude-newer = "3 days"