[tests] Add CodSpeed benchmark for compiled-config cache fast path (#16402)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

tests/benchmarks/python/conftest.py

@@ -0,0 +1,22 @@
+"""Shared fixtures for the Python benchmark suite."""
+
+from __future__ import annotations
+
+from collections.abc import Generator
+
+import pytest
+
+from esphome.core import CORE
+
+
+@pytest.fixture(autouse=True)
+def reset_core_state() -> Generator[None]:
+    """Reset CORE before and after every benchmark.
+
+    Per-iteration setups inside benchmarks reset CORE for the loop body;
+    this fixture handles the test-level boundary so stale state from
+    fixture priming doesn't leak across benchmarks.
+    """
+    CORE.reset()
+    yield
+    CORE.reset()