phsl / new-api

Summary
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1. **Backend**
   • `model/model_meta.go`
     – Add `GetBoundChannelsForModels([]string)` to retrieve channels for multiple models in a single SQL (`IN (?)`) and deduplicate with `GROUP BY`.

   • `controller/model_meta.go`
     – In non-exact `fillModelExtra`:
       – Remove per-model `GetBoundChannels` calls.
       – Collect matched model names, then call `GetBoundChannelsForModels` once and merge results into `channelSet`.
       – Minor cleanup on loop logic; channel aggregation now happens after quota/group/endpoint processing.

Impact
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• Eliminates N+1 query pattern for prefix/suffix/contains rules.
• Reduces DB round-trips from *N + 1* to **1**, markedly speeding up the model-management list load.
• Keeps existing `GetBoundChannels` API intact for single-model scenarios; no breaking changes.