feat(Sku): support disable_status field to filter disabled SKU options

[Yvan0423-code]

🎯 Overview

Add support for disable_status field in SKU component to automatically filter disabled SKU options and improve user experience.

✨ Features

• Auto filter disabled SKUs: Hide SKU options with disable_status: 1
• Smart cascading filter: Filter out options that would result in all disabled combinations
• Initialization check: Validate initialSku to ensure valid selection on component init

🔧 Implementation

Filtering Rules

1. Hide spec values if all related SKUs are disabled
2. Filter out spec values that create only disabled combinations when selected
3. Hide spec categories with no available values
4. Check initialSku validity during initialization

Core Changes

• Add filterDisabledSkuTree function for filtering logic
• Enhance isSkuChoosable to check non-disabled SKU stock
• Update resetSelectedSku with disabled status validation
• Add checkInitialSkuDisabled method for initial validation

📝 Data Structure

New disable_status field in SKU list:

{
  id: 2258,
  s1: '1', 
  s2: '2',
  price: 100,
  stock_num: 6,
  disable_status: 1  // 0: available, 1: disabled
}

📚 Documentation

Updated README.md with "Disabled SKU" section explaining the filtering mechanism and rules.

🔄 Backward Compatibility

Fully backward compatible - SKUs without disable_status or with value 0 maintain original behavior.

This feature is ideal for e-commerce scenarios requiring dynamic spec filtering, such as seasonal or limited products.

[chenjiahan]

released: https://www.npmjs.com/package/vant/v/2.13.9-beta.0