feat: module-driven onboarding system + simplified 3-step signup

Add OnboardingProviderProtocol so modules declare their own post-signup
onboarding steps. The core OnboardingAggregator discovers enabled
providers and exposes a dashboard API (GET /dashboard/onboarding).
A session-scoped banner on the store dashboard shows a checklist that
guides merchants through setup without blocking signup.

Signup is simplified from 4 steps to 3 (Plan → Account → Payment):
store creation is merged into account creation, store language is
captured from the user's browsing language, and platform-specific
template branching is removed.

Includes 47 unit and integration tests covering all new providers,
the aggregator, the API endpoint, and the signup service changes.

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

app/modules/core/tests/integration/test_onboarding_routes.py

@@ -0,0 +1,215 @@
+# app/modules/core/tests/integration/test_onboarding_routes.py
+"""
+Integration tests for the onboarding API endpoint.
+
+Tests the store dashboard onboarding endpoint at:
+    GET /api/v1/store/dashboard/onboarding
+
+Verifies:
+- Endpoint returns onboarding steps with completion status
+- Endpoint requires store authentication
+- Response structure matches expected schema
+"""
+
+import uuid
+
+import pytest
+
+from app.api.deps import get_current_store_api
+from app.modules.tenancy.models import Merchant, Platform, Store, User
+from app.modules.tenancy.models.store_platform import StorePlatform
+from app.modules.tenancy.schemas.auth import UserContext
+from main import app
+
+# ============================================================================
+# Fixtures
+# ============================================================================
+
+
+@pytest.fixture
+def onb_owner(db):
+    """Create a store owner user for onboarding tests."""
+    from middleware.auth import AuthManager
+
+    auth = AuthManager()
+    user = User(
+        email=f"onbroute_{uuid.uuid4().hex[:8]}@test.com",
+        username=f"onbroute_{uuid.uuid4().hex[:8]}",
+        hashed_password=auth.hash_password("pass123"),
+        role="merchant_owner",
+        is_active=True,
+    )
+    db.add(user)
+    db.commit()
+    db.refresh(user)
+    return user
+
+
+@pytest.fixture
+def onb_platform(db):
+    """Create a platform for onboarding tests."""
+    platform = Platform(
+        code=f"onbp_{uuid.uuid4().hex[:8]}",
+        name="Onboarding Test Platform",
+        is_active=True,
+    )
+    db.add(platform)
+    db.commit()
+    db.refresh(platform)
+    return platform
+
+
+@pytest.fixture
+def onb_merchant(db, onb_owner):
+    """Create a merchant for onboarding tests."""
+    merchant = Merchant(
+        name="Onboarding Route Test Merchant",
+        owner_user_id=onb_owner.id,
+        contact_email=onb_owner.email,
+        is_active=True,
+        is_verified=True,
+    )
+    db.add(merchant)
+    db.commit()
+    db.refresh(merchant)
+    return merchant
+
+
+@pytest.fixture
+def onb_store(db, onb_merchant):
+    """Create a store for onboarding tests."""
+    uid = uuid.uuid4().hex[:8]
+    store = Store(
+        merchant_id=onb_merchant.id,
+        store_code=f"ONBROUTE_{uid.upper()}",
+        subdomain=f"onbroute{uid.lower()}",
+        name="Onboarding Route Test Store",
+        is_active=True,
+        is_verified=True,
+    )
+    db.add(store)
+    db.commit()
+    db.refresh(store)
+    return store
+
+
+@pytest.fixture
+def onb_store_platform(db, onb_store, onb_platform):
+    """Link store to platform."""
+    sp = StorePlatform(
+        store_id=onb_store.id,
+        platform_id=onb_platform.id,
+        is_active=True,
+    )
+    db.add(sp)
+    db.commit()
+    db.refresh(sp)
+    return sp
+
+
+@pytest.fixture
+def onb_auth(onb_owner, onb_store):
+    """Override auth dependency for store API auth."""
+    user_context = UserContext(
+        id=onb_owner.id,
+        email=onb_owner.email,
+        username=onb_owner.username,
+        role="merchant_owner",
+        is_active=True,
+        token_store_id=onb_store.id,
+        token_store_code=onb_store.store_code,
+    )
+
+    def _override():
+        return user_context
+
+    app.dependency_overrides[get_current_store_api] = _override
+    yield {"Authorization": "Bearer fake-token"}
+    app.dependency_overrides.pop(get_current_store_api, None)
+
+
+# ============================================================================
+# Tests
+# ============================================================================
+
+
+@pytest.mark.integration
+@pytest.mark.core
+class TestOnboardingEndpoint:
+    """Tests for GET /api/v1/store/dashboard/onboarding."""
+
+    def test_returns_onboarding_summary(
+        self, client, db, onb_auth, onb_store, onb_store_platform
+    ):
+        """Endpoint returns onboarding summary with expected structure."""
+        response = client.get(
+            "/api/v1/store/dashboard/onboarding",
+            headers=onb_auth,
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        assert "steps" in data
+        assert "total_steps" in data
+        assert "completed_steps" in data
+        assert "progress_percentage" in data
+        assert "all_completed" in data
+        assert isinstance(data["steps"], list)
+        assert isinstance(data["total_steps"], int)
+        assert isinstance(data["completed_steps"], int)
+
+    def test_includes_tenancy_step(
+        self, client, db, onb_auth, onb_store, onb_store_platform
+    ):
+        """Response includes the tenancy customize_store step (always present)."""
+        response = client.get(
+            "/api/v1/store/dashboard/onboarding",
+            headers=onb_auth,
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        step_keys = [s["key"] for s in data["steps"]]
+        assert "tenancy.customize_store" in step_keys
+
+    def test_step_data_has_required_fields(
+        self, client, db, onb_auth, onb_store, onb_store_platform
+    ):
+        """Each step has key, title_key, description_key, icon, route, completed."""
+        response = client.get(
+            "/api/v1/store/dashboard/onboarding",
+            headers=onb_auth,
+        )
+        data = response.json()
+
+        for step in data["steps"]:
+            assert "key" in step
+            assert "title_key" in step
+            assert "description_key" in step
+            assert "icon" in step
+            assert "route" in step
+            assert "completed" in step
+            assert isinstance(step["completed"], bool)
+
+    def test_routes_contain_store_code(
+        self, client, db, onb_auth, onb_store, onb_store_platform
+    ):
+        """Step routes have {store_code} replaced with the actual store code."""
+        response = client.get(
+            "/api/v1/store/dashboard/onboarding",
+            headers=onb_auth,
+        )
+        data = response.json()
+
+        for step in data["steps"]:
+            assert "{store_code}" not in step["route"]
+            if "/store/" in step["route"]:
+                assert onb_store.store_code in step["route"]
+
+    def test_requires_auth(self, client):
+        """Returns 401 without authentication."""
+        app.dependency_overrides.pop(get_current_store_api, None)
+        response = client.get(
+            "/api/v1/store/dashboard/onboarding",
+        )
+        assert response.status_code == 401