Update admin theme/layout and refresh README details.

Align the project baseline with the latest admin interface styling and layout structure while documenting setup and usage updates in README.

apps/api/tests/conftest.py

@@ -0,0 +1,50 @@
+import os
+
+os.environ.setdefault("DATABASE_URL", "sqlite+pysqlite:///:memory:")
+os.environ.setdefault("EMAIL_DELIVERY_MODE", "memory")
+
+from fastapi.testclient import TestClient
+import pytest
+
+from app.core import database as db_module
+from app.core.email import memory_mailer
+from app.core.storage import memory_store
+from app.db.base import Base
+from app.db.seed import run_seed
+from app.main import app
+
+
+@pytest.fixture(scope="session", autouse=True)
+def setup_database():
+    Base.metadata.create_all(db_module.engine)
+    run_seed(include_demo_pages=False)
+    yield
+    Base.metadata.drop_all(db_module.engine)
+
+
+@pytest.fixture(autouse=True)
+def disable_rate_limits(monkeypatch):
+    from app.core.config import settings
+
+    monkeypatch.setattr(settings, "enable_rate_limit", False)
+    monkeypatch.setattr(settings, "email_delivery_mode", "memory")
+    monkeypatch.setattr(settings, "storage_mode", "memory")
+
+
+@pytest.fixture(autouse=True)
+def clear_email_outbox():
+    memory_mailer.clear()
+    yield
+    memory_mailer.clear()
+
+
+@pytest.fixture(autouse=True)
+def clear_storage():
+    memory_store.clear()
+    yield
+    memory_store.clear()
+
+
+@pytest.fixture()
+def client() -> TestClient:
+    return TestClient(app)