Complete spec: Code alignment and documentation cleanup

- Ensure code aligns with CentralDB models
- Document code alignment with CentralDB models
- Remove informal reference documents (data-model.md, DB_API_SPEC.json, GARMINSYNC_SPEC.md)
- Run linters and formatters (black, isort, mypy)
- Update project configuration files
- Add .dockerignore for Docker builds
- Perform code formatting and import sorting
- Fix type checking issues
- Update documentation files
- Complete implementation tasks as per spec

backend/tests/unit/test_central_db_models.py

@@ -0,0 +1,73 @@
+from datetime import datetime
+
+from backend.src.models.central_db_models import (
+    Activity,
+    GarminConnectAccount,
+    GarminCredentials,
+    HealthMetric,
+    User,
+    Workout,
+)
+
+
+def test_user_model():
+    user = User(id="123", username="testuser", email="test@example.com")
+    assert user.id == "123"
+    assert user.username == "testuser"
+    assert user.email == "test@example.com"
+
+
+def test_garmin_connect_account_model():
+    account = GarminConnectAccount(
+        id="abc",
+        user_id="123",
+        oauth_token="token",
+        oauth_token_secret="secret",
+        refresh_token="refresh",
+        token_expires_at=datetime.now(),
+    )
+    assert account.id == "abc"
+    assert account.user_id == "123"
+
+
+def test_garmin_credentials_model():
+    credentials = GarminCredentials(
+        garmin_username="garmin@example.com",
+        garmin_password_plaintext="password",
+        access_token="access",
+        access_token_secret="access_secret",
+        token_expiration_date=datetime.now(),
+    )
+    assert credentials.garmin_username == "garmin@example.com"
+
+
+def test_activity_model():
+    activity = Activity(
+        id="act1",
+        user_id="123",
+        garmin_activity_id="gact1",
+        activity_type="running",
+        start_time=datetime.now(),
+    )
+    assert activity.id == "act1"
+
+
+def test_health_metric_model():
+    metric = HealthMetric(
+        id="hm1",
+        user_id="123",
+        metric_type="heart_rate",
+        timestamp=datetime.now(),
+        value=70.5,
+    )
+    assert metric.id == "hm1"
+
+
+def test_workout_model():
+    workout = Workout(
+        id="wk1",
+        user_id="123",
+        name="Morning Run",
+        workout_definition={"steps": []},
+    )
+    assert workout.id == "wk1"