当模型配置了渠道定价但全局定价未设置时，不再提前报错。
将全局定价检查延迟到渠道选择后执行。

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

This PR fixes three issues:
1. Token bound_channel_id not updating: Add bound field to Update() method
2. Channel pricing quota_type detection: Use QuotaTypeByCall constant instead of magic number 1
3. Log display for ratio-based pricing: Set ModelPrice=-1 for ratio-based pricing

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

Integrate channel-specific pricing into the billing logic.
- First tries to get channel pricing using model.GetEffectivePricing
- If found, uses channel pricing (modelRatio, completionRatio, modelPrice, usePrice)
- If not found, falls back to global pricing from ratio_setting

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