Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- GetAllChannelPricing: get all channel pricings with pagination
- GetChannelPricingByModel: get pricings for a specific model
- CreateChannelPricing: create or update channel pricing
- BatchCreateChannelPricing: batch create/update pricings
- DeleteChannelPricing: delete channel pricing
- CopyGlobalPricing: copy global pricing from ratio_setting to channel
- GetChannelPricingWithTags: get pricings with tag details

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>