feat(billing): B4-B5 — tests, lint fixes, CHANGELOG + PROJECT.md

- Fix unused imports in stripe.py (hashlib, hmac, time)
- Update test_billing_routes.py: insert into payment_products table,
  fix mock paths for extracted paddle.py, add Stripe webhook 404 test
- Update CHANGELOG.md with Stripe provider feature
- Update PROJECT.md Done section

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

web/src/padelnomics/billing/stripe.py

@@ -12,11 +12,8 @@ Exports the same interface as paddle.py so billing/routes.py can dispatch:
 Stripe Tax add-on handles EU VAT collection (must be enabled in Stripe Dashboard).
 """
 
-import hashlib
-import hmac
 import json
 import logging
-import time
 
 import stripe as stripe_sdk
 

web/tests/test_billing_routes.py

@@ -1,6 +1,7 @@
 """
-Route integration tests for Paddle billing endpoints.
-Checkout uses Paddle.js overlay (returns JSON), manage/cancel use Paddle SDK.
+Route integration tests for billing endpoints.
+Tests work with the default provider (Paddle) via dispatch layer.
+Checkout returns JSON (Paddle overlay or Stripe redirect URL), manage/cancel use provider SDK.
 """
 from unittest.mock import MagicMock, patch
 
@@ -39,7 +40,24 @@ class TestSuccessPage:
 
 
 # ════════════════════════════════════════════════════════════
-# Checkout (Paddle.js overlay — returns JSON)
+# Helper: insert a product into both payment_products and paddle_products
+# ════════════════════════════════════════════════════════════
+
+async def _insert_test_product(db, key="starter", price_id="pri_starter_123"):
+    """Insert a test product into payment_products (used by get_price_id) and paddle_products (legacy fallback)."""
+    await db.execute(
+        "INSERT INTO payment_products (provider, key, provider_product_id, provider_price_id, name, price_cents, currency, billing_type) VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
+        ("paddle", key, "pro_test", price_id, "Starter", 1900, "EUR", "subscription"),
+    )
+    await db.execute(
+        "INSERT INTO paddle_products (key, paddle_product_id, paddle_price_id, name, price_cents, currency, billing_type) VALUES (?, ?, ?, ?, ?, ?, ?)",
+        (key, "pro_test", price_id, "Starter", 1900, "EUR", "subscription"),
+    )
+    await db.commit()
+
+
+# ════════════════════════════════════════════════════════════
+# Checkout (returns JSON — Paddle overlay or Stripe redirect)
 # ════════════════════════════════════════════════════════════
 
 class TestCheckoutRoute:
@@ -48,12 +66,7 @@ class TestCheckoutRoute:
         assert response.status_code in (302, 303, 307)
 
     async def test_returns_checkout_json(self, auth_client, db, test_user):
-        # Insert a paddle_products row so get_paddle_price() finds it
-        await db.execute(
-            "INSERT INTO paddle_products (key, paddle_product_id, paddle_price_id, name, price_cents, currency, billing_type) VALUES (?, ?, ?, ?, ?, ?, ?)",
-            ("starter", "pro_test", "pri_starter_123", "Starter", 1900, "EUR", "subscription"),
-        )
-        await db.commit()
+        await _insert_test_product(db)
 
         response = await auth_client.post(f"/billing/checkout/{CHECKOUT_PLAN}")
         assert response.status_code == 200
@@ -89,7 +102,7 @@ class TestManageRoute:
         mock_client = MagicMock()
         mock_client.subscriptions.get.return_value = mock_sub
 
-        with patch("padelnomics.billing.routes._paddle_client", return_value=mock_client):
+        with patch("padelnomics.billing.paddle._paddle_client", return_value=mock_client):
             response = await auth_client.post("/billing/manage", follow_redirects=False)
         assert response.status_code in (302, 303, 307)
 
@@ -111,12 +124,27 @@ class TestCancelRoute:
         await create_subscription(test_user["id"], provider_subscription_id="sub_test")
 
         mock_client = MagicMock()
-        with patch("padelnomics.billing.routes._paddle_client", return_value=mock_client):
+        with patch("padelnomics.billing.paddle._paddle_client", return_value=mock_client):
             response = await auth_client.post("/billing/cancel", follow_redirects=False)
         assert response.status_code in (302, 303, 307)
         mock_client.subscriptions.cancel.assert_called_once()
 
 
+# ════════════════════════════════════════════════════════════
+# Stripe webhook returns 404 when not configured
+# ════════════════════════════════════════════════════════════
+
+class TestStripeWebhookEndpoint:
+    async def test_returns_404_when_not_configured(self, client, db):
+        """Stripe webhook returns 404 when STRIPE_WEBHOOK_SECRET is empty."""
+        response = await client.post(
+            "/billing/webhook/stripe",
+            data=b'{}',
+            headers={"Content-Type": "application/json"},
+        )
+        assert response.status_code == 404
+
+
 # ════════════════════════════════════════════════════════════
 # subscription_required decorator
 # ════════════════════════════════════════════════════════════