Add config and client injection with test reorganization.

Introduce typed config objects, optional adapter injection, and .env loading to simplify testing while preserving env-based defaults for production usage.

Co-authored-by: Cursor <[email protected]>

tests/unit/dotenv_loader_test.py

@@ -0,0 +1,26 @@
+"""Unit tests for dotenv_loader."""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+import pytest
+
+from python_repositories.config.dotenv_loader import load_dotenv
+
+
+def test_load_dotenv_loads_file(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    env_file = tmp_path / ".env"
+    env_file.write_text("DOTENV_TEST_VAR=loaded_value\n")
+    monkeypatch.delenv("DOTENV_TEST_VAR", raising=False)
+    loaded = load_dotenv(env_file)
+    assert loaded is True
+    assert os.getenv("DOTENV_TEST_VAR") == "loaded_value"
+
+
+def test_load_dotenv_returns_false_for_missing_file(tmp_path: Path) -> None:
+    missing = tmp_path / "missing.env"
+    assert load_dotenv(missing) is False