feat(pytest-plugin): add plugin hooks and markers

Register text_validation marker via pytest_configure hook.

src/veritext/pytest_plugin/__init__.py

@@ -0,0 +1,22 @@
+"""Pytest plugin for text validation.
+
+This plugin provides native pytest integration for Veritext, enabling
+text validation assertions in test suites.
+
+Example:
+    >>> from veritext.pytest_plugin import validate_text
+    >>>
+    >>> def test_summary_quality():
+    ...     text = "The quick brown fox jumps over the lazy dog."
+    ...     validate_text(
+    ...         text,
+    ...         min_length=10,
+    ...         max_length=100,
+    ...         max_reading_grade=8.0,
+    ...     )
+"""
+
+from veritext.pytest_plugin.assertions import validate_text
+from veritext.pytest_plugin.plugin import pytest_configure
+
+__all__ = ["pytest_configure", "validate_text"]

src/veritext/pytest_plugin/plugin.py

@@ -0,0 +1,18 @@
+"""Pytest hooks for Veritext plugin."""
+
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    import pytest
+
+
+def pytest_configure(config: "pytest.Config") -> None:
+    """Register Veritext markers.
+
+    Args:
+        config: Pytest configuration object.
+    """
+    config.addinivalue_line(
+        "markers",
+        "text_validation: mark test as a text validation test",
+    )