Default variant detection breaks on non-English markets

[hta218]

Description

Detection of Shopify's synthetic single-variant option ("Title" / "Default Title") is hardcoded to the English option name. Shopify translates the option name per market (on /de it renders as "Titel"), so the check fails and the placeholder leaks into the UI: the variant selector renders on single-variant PDPs showing Titel: Default Title, and the placeholder appears in cart and bundle labels.

In the markets observed so far the option name is translated while the value still reads "Default Title" — so requiring both sides with && is what breaks. Note the value and the variant title are translatable resources too, so a fix should not depend on any single one of them staying English.

Affected code

• app/utils/product.ts — hasOnlyDefaultVariant() requires option.name === "Title"
• app/components/cart/cart-line-item.tsx — isDefaultVariant = name === "Title" && value === "Default Title"
• app/components/product/bundled-variants.tsx — bundledVariant.title !== "Default Title"

Suggested fix

• Normalize (trim + lowercase) and match against a shared marker set (title, default title) instead of exact English strings.
• Accept any side that still carries the untranslated marker (|| instead of &&): option value, option name, or the variant title.
• For hasOnlyDefaultVariant(), require the structural shape first (exactly one option with exactly one value), then the marker check.
• Expose shared helpers (e.g. isDefaultTitleOption, isDefaultVariantTitle) so all three call sites use one implementation.

Keep genuine single-value options (Size: One size, Color: Black) rendering — a purely structural check (one option / one value) would hide those too, which is not what we want.

Steps to reproduce

1. Open a single-variant product PDP on a non-English market (e.g. /de).
2. Observe the variant selector renders with Titel: Default Title instead of being hidden.
3. Add the item to cart and observe the placeholder in the cart line options.