Cart Peek: real-time cart social proof for WooCommerce (Free)

[ShahrearMSf]

NotificationX's Sales notifications show past purchases — shoppers read them as history — but the moment that actually decides a sale is the hesitation right before Add-to-Cart, which nothing in the plugin covers today.
Cart Peek closes that gap with a truthful, real-time "N shoppers have this in their cart" card, turning the highest-intent object in the store — the cart — into live social proof that lifts product-page conversion.
Research backing the impact is linked at the bottom.

Summary

Adds the new Cart Peek notification type to the WooCommerce family — a live social-proof card ("N shoppers have this in their cart") shown on product/shop pages. This PR is the Free half: the notification type, its themes, the builder fields, and registration. The live-count engine + exit-intent popup ship in the Pro companion PR (Cart Peek extends this Free stub via the namespace-swap pattern).

Feature proposal / spec: https://gist.github.com/ShahrearMSf/ea5b506a7094a95230ece859a12e834b

What's in this PR

• Types/WooCommerceCartPeek.php — new Pro-badged Conversions-family type. 6 desktop + 3 mobile themes (rendered through the existing Sales conversion pipeline — no new frontend paradigm), plus Customize-tab fields for the shopper-facing cart-confirmation popup (heading, button labels, and count/list/total multi-product display).
• Extensions/WooCommerce/WooCommerceCartPeek.php — Free WooCommerce source stub (WooCommerce icon + "WooCommerce" source title); all runtime behaviour lives in the Pro override.
• Types/TypesFactory.php, Extensions/ExtensionFactory.php — register the type + extension.
• assets/admin/images/extensions/themes/cart-peek/ — 9 theme preview thumbnails (6 desktop, 3 mobile).
• vendor/composer/autoload_*.php — classmap entries for the two new classes only.

How it works (Free side)

• Registers the Cart Peek card in Add New and Quick Builder; shows the PRO badge + upgrade popup in Free-only mode, consistent with other Pro types.
• Themes reuse the compiled Sales conversion designs, so the feature ships without a frontend rebuild.
• Per the Free/Pro scope split in the spec, Free is the hook + upsell surface; the live counting, threshold rules, custom copy and analytics are Pro.

Testing

• php -l clean on all changed/added PHP files; no fatals in debug.log.
• Cart Peek card renders in both Add New and Quick Builder.
• PRO crown badge shows in Free-only mode, matching the other Pro types.
• Design tab shows all 6 desktop + 3 mobile theme previews.

Notes

• Requires the companion notificationx-pro PR for live behaviour.
• Privacy-first by design: no PII is introduced by this type.

Research & references (impact case)

• Baymard Institute — average cart abandonment ~70.2% (50 studies): https://baymard.com/lists/cart-abandonment-rate
• Contentsquare — cart abandonment stats: https://contentsquare.com/guides/cart-abandonment/stats/
• Monetate — social proof and conversion: https://monetate.com/resource/social-proof/
• Abmatic — scarcity & urgency in CRO: https://abmatic.ai/blog/role-of-scarcity-and-urgency-in-conversion-rate-optimization