Add EvoSync v3 environment scaffold

FastAPI + Celery + Redis + MariaDB stack with 6-service docker-compose.
Includes project skeleton (config, database, models, tasks, migrations)
and health endpoint with passing test.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/conftest.py

@@ -0,0 +1,25 @@
+import pytest
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from web.database import Base
+
+
+@pytest.fixture(scope="session")
+def engine():
+    eng = create_engine("sqlite:///:memory:", echo=False)
+    Base.metadata.create_all(eng)
+    yield eng
+    Base.metadata.drop_all(eng)
+
+
+@pytest.fixture
+def db_session(engine):
+    connection = engine.connect()
+    transaction = connection.begin()
+    Session = sessionmaker(bind=connection)
+    session = Session()
+    yield session
+    session.close()
+    transaction.rollback()
+    connection.close()