test: add tests for merchant dashboard metrics and fix invoice template location

Move invoice PDF template from app/templates/invoices/ to
app/modules/orders/templates/invoices/ where InvoicePDFService expects it.
Expand invoice PDF tests to validate template path and existence.

Add unit tests for get_merchant_metrics() in tenancy, billing, and
customer metrics providers. Add unit tests for StatsAggregatorService
merchant methods. Add integration tests for the merchant dashboard
stats endpoint.

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

app/modules/tenancy/tests/unit/test_tenancy_metrics.py

@@ -0,0 +1,132 @@
+# app/modules/tenancy/tests/unit/test_tenancy_metrics.py
+"""Unit tests for TenancyMetricsProvider.get_merchant_metrics."""
+
+import uuid
+
+import pytest
+
+from app.modules.tenancy.models import Merchant, Store, StoreUser, User
+from app.modules.tenancy.services.tenancy_metrics import TenancyMetricsProvider
+
+
+@pytest.fixture
+def metrics_merchant(db):
+    """Create a merchant owner and merchant for metrics tests."""
+    from middleware.auth import AuthManager
+
+    auth = AuthManager()
+    user = User(
+        email=f"metricsowner_{uuid.uuid4().hex[:8]}@test.com",
+        username=f"metricsowner_{uuid.uuid4().hex[:8]}",
+        hashed_password=auth.hash_password("pass123"),
+        role="merchant_owner",
+        is_active=True,
+    )
+    db.add(user)
+    db.flush()
+
+    merchant = Merchant(
+        name="Metrics Test Merchant",
+        owner_user_id=user.id,
+        contact_email=user.email,
+        is_active=True,
+        is_verified=True,
+    )
+    db.add(merchant)
+    db.commit()
+    db.refresh(merchant)
+    return merchant
+
+
+@pytest.fixture
+def metrics_stores(db, metrics_merchant):
+    """Create 3 stores (2 active, 1 inactive) for the merchant."""
+    stores = []
+    for i, active in enumerate([True, True, False]):
+        uid = uuid.uuid4().hex[:8].upper()
+        store = Store(
+            merchant_id=metrics_merchant.id,
+            store_code=f"MSTORE_{uid}",
+            subdomain=f"mstore{uid.lower()}",
+            name=f"Metrics Store {i}",
+            is_active=active,
+            is_verified=True,
+        )
+        db.add(store)
+        stores.append(store)
+    db.commit()
+    for s in stores:
+        db.refresh(s)
+    return stores
+
+
+@pytest.fixture
+def metrics_team_members(db, metrics_stores):
+    """Create team members across merchant stores."""
+    from middleware.auth import AuthManager
+
+    auth = AuthManager()
+    users = []
+    for i in range(3):
+        u = User(
+            email=f"team_{uuid.uuid4().hex[:8]}@test.com",
+            username=f"team_{uuid.uuid4().hex[:8]}",
+            hashed_password=auth.hash_password("pass123"),
+            role="store_user",
+            is_active=True,
+        )
+        db.add(u)
+        users.append(u)
+    db.flush()
+
+    # User 0 on store 0 and store 1 (should be counted once)
+    db.add(StoreUser(store_id=metrics_stores[0].id, user_id=users[0].id, is_active=True))
+    db.add(StoreUser(store_id=metrics_stores[1].id, user_id=users[0].id, is_active=True))
+    # User 1 on store 0 only
+    db.add(StoreUser(store_id=metrics_stores[0].id, user_id=users[1].id, is_active=True))
+    # User 2 on store 0 but inactive
+    db.add(StoreUser(store_id=metrics_stores[0].id, user_id=users[2].id, is_active=False))
+    db.commit()
+    return users
+
+
+@pytest.mark.unit
+@pytest.mark.tenancy
+class TestTenancyMetricsProviderMerchant:
+    """Tests for TenancyMetricsProvider.get_merchant_metrics."""
+
+    def setup_method(self):
+        self.provider = TenancyMetricsProvider()
+
+    def test_total_stores(self, db, metrics_merchant, metrics_stores):
+        """Returns correct total store count for merchant."""
+        metrics = self.provider.get_merchant_metrics(db, metrics_merchant.id)
+        by_key = {m.key: m.value for m in metrics}
+        assert by_key["tenancy.total_stores"] == 3
+
+    def test_active_stores(self, db, metrics_merchant, metrics_stores):
+        """Returns correct active store count (excludes inactive)."""
+        metrics = self.provider.get_merchant_metrics(db, metrics_merchant.id)
+        by_key = {m.key: m.value for m in metrics}
+        assert by_key["tenancy.active_stores"] == 2
+
+    def test_team_members_distinct(self, db, metrics_merchant, metrics_stores, metrics_team_members):
+        """Counts distinct active team members across stores."""
+        metrics = self.provider.get_merchant_metrics(db, metrics_merchant.id)
+        by_key = {m.key: m.value for m in metrics}
+        # 2 active distinct users (user 0 on 2 stores counted once, user 1, user 2 inactive)
+        assert by_key["tenancy.team_members"] == 2
+
+    def test_no_stores(self, db, metrics_merchant):
+        """Returns zero counts when merchant has no stores."""
+        metrics = self.provider.get_merchant_metrics(db, metrics_merchant.id)
+        by_key = {m.key: m.value for m in metrics}
+        assert by_key["tenancy.total_stores"] == 0
+        assert by_key["tenancy.active_stores"] == 0
+        assert by_key["tenancy.team_members"] == 0
+
+    def test_nonexistent_merchant(self, db):
+        """Returns zero counts for a non-existent merchant ID."""
+        metrics = self.provider.get_merchant_metrics(db, 999999)
+        by_key = {m.key: m.value for m in metrics}
+        assert by_key["tenancy.total_stores"] == 0