Add product thumbnail to back-in-stock email, left-align notify button text

renderBackInStockHtml() (and sendBackInStockEmails.ts on the backend)
now show a small product image above the product name, when the
product has one. Also left-aligns NotifyMeForm's button text to match
the email input's own left-aligned placeholder — was centered, read
as inconsistent next to it.

Also adds the klaro dependency, ahead of swapping the custom cookie
banner for it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package.json

@@ -16,6 +16,7 @@
     "@react-pdf/renderer": "^4.5.1",
     "@stripe/react-stripe-js": "^6.8.0",
     "@stripe/stripe-js": "^9.12.0",
+    "klaro": "^0.7.21",
     "motion": "^12.42.2",
     "next": "16.2.9",
     "nodemailer": "^9.0.3",