Add Postgres table adapter with TableRepositoryInterface.

Introduce PostgresAdapter for dict-based row CRUD via psycopg3, including config, lazy exports, unit/integration tests with testcontainers, and an example UserTableRepository.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/integration/examples/conftest.py

@@ -6,7 +6,7 @@ from minio import Minio
 import pytest
 import redis
 
-from python_repositories.config import MinioConfig, RedisConfig
+from python_repositories.config import MinioConfig, PostgresConfig, RedisConfig
 from tests.integration.minio._containers import (
     minio_config_from_env,
     minio_env,
@@ -17,6 +17,11 @@ from tests.integration.redis._containers import (
     redis_config_from_container,
     redis_uri,
 )
+from tests.integration.postgres._containers import (
+    postgres_config_from_container,
+    postgres_uri,
+    raw_postgres_client_from_container,
+)
 
 
 @pytest.fixture(scope="session")
@@ -53,3 +58,23 @@ def minio_config(minio_container: dict[str, str]) -> MinioConfig:
 def raw_minio_client(minio_container: dict[str, str]) -> Generator[Minio, None, None]:
     """Provide a raw Minio client connected to the test Minio container."""
     yield from raw_minio_client_from_env(minio_container)
+
+
+@pytest.fixture(scope="session")
+def postgres_container() -> Generator[str, None, None]:
+    """Set up a Postgres container for testing and yield the Postgres URI."""
+    yield from postgres_uri()
+
+
+@pytest.fixture(scope="session")
+def postgres_config(postgres_container: str) -> PostgresConfig:
+    """Provide PostgresConfig built from the test container."""
+    return postgres_config_from_container(postgres_container)
+
+
+@pytest.fixture(scope="session")
+def raw_postgres_client(
+    postgres_container: str,
+) -> Generator[object, None, None]:
+    """Provide a raw Postgres client connected to the test Postgres container."""
+    yield from raw_postgres_client_from_container(postgres_container)