feat(models): Added TestRunner class

TestRunner orchestrates test execution:
- Executor: sends HTTP requests
- Extractor: extracts data from responses
- Validator: checks assertions
- Returns TestResult with pass/fail status

models/runner.py

@@ -0,0 +1,38 @@
+from .itm import TestModel
+from .context import Context
+from .executor import Executor, Response
+from .extractor import Extractor
+from .validator import Validator
+
+
+class StepResult:
+    def __init__(self, name: str, passed: bool, response: Response):
+        self.name = name
+        self.passed = passed
+        self.response = response
+
+
+class TestResult:
+    def __init__(self, steps: list[StepResult]):
+        self.steps = steps
+
+    @property
+    def passed(self) -> bool:
+        return all(s.passed for s in self.steps)
+
+
+class TestRunner:
+    def __init__(self, context: Context):
+        self.context = context
+        self.executor = Executor(context)
+        self.extractor = Extractor(context)
+        self.validator = Validator()
+
+    def run(self) -> TestResult:
+        results = []
+        for step in self.context.config.steps:
+            response = self.executor.execute(step.request)
+            self.extractor.extract(step.extract, response)
+            passed = self.validator.validate(step.assert_, response)
+            results.append(StepResult(step.name, passed, response))
+        return TestResult(results)