Variant-Level Upsells and Priority Control

New Features

• Variant-level upsell targeting: Create upsell rules for specific product variants instead of entire products
• Rule priority control: Set priority for upsell rules (lower numbers appear first)

• Product ordering within rules: Drag to reorder upsell products within each rule
• Mixed upsell rules: Combine complete products, specific variants, and collections in the same rule
• Custom subtitles for upsells: Add personalized messages for each upsell product (e.g. “Frequently bought together”)

Upsell Rule Improvements

• New product/variant selector with hierarchical view (product → variants)
• Select complete products (shows variant dropdown in cart) or specific variants (direct add button)
• Improved upsell deduplication logic to prevent duplicate recommendations
• Better rule matching for variant-specific conditions

Fixes

• Fix SaveBar not triggering on floating cart button settings changes
• Fix product removal in rule conditions (When section)
• Fix duplicate upsells appearing in cart drawer
• Fix incorrect rule priority ordering for collection-based rules