🚀 perf: optimize model management APIs, unify pricing types as array, and remove redundancies

Backend
- Add GetBoundChannelsByModelsMap to batch-fetch bound channels via a single JOIN (Distinct), compatible with SQLite/MySQL/PostgreSQL
- Replace per-record enrichment with a single-pass enrichModels to avoid N+1 queries; compute unions for prefix/suffix/contains matches in memory
- Change Model.QuotaType to QuotaTypes []int and expose quota_types in responses
- Add GetModelQuotaTypes for cached O(1) lookups; exact models return a single-element array
- Sort quota_types for stable output order
- Remove unused code: GetModelByName, GetBoundChannels, GetBoundChannelsForModels, FindModelByNameWithRule, buildPrefixes, buildSuffixes
- Clean up redundant comments, keeping concise and readable code

Frontend
- Models table: switch to quota_types, render multiple billing modes ([0], [1], [0,1], future values supported)
- Pricing table: switch to quota_types; ratio display now checks quota_types.includes(0); array rendering for billing tags

Compatibility
- SQL uses standard JOIN/IN/Distinct; works across SQLite/MySQL/PostgreSQL
- Lint passes; no DB schema changes (quota_types is a JSON response field only)

Breaking Change
- API field renamed: quota_type -> quota_types (array). Update clients accordingly.

model/model_extra.go

@@ -1,7 +1,5 @@
 package model
 
-// GetModelEnableGroups 返回指定模型名称可用的用户分组列表。
-// 使用在 updatePricing() 中维护的缓存映射，O(1) 读取，适合高并发场景。
 func GetModelEnableGroups(modelName string) []string {
 	// 确保缓存最新
 	GetPricing()
@@ -19,16 +17,15 @@ func GetModelEnableGroups(modelName string) []string {
 	return groups
 }
 
-// GetModelQuotaType 返回指定模型的计费类型（quota_type）。
-// 同样使用缓存映射，避免每次遍历定价切片。
-func GetModelQuotaType(modelName string) int {
+// GetModelQuotaTypes 返回指定模型的计费类型集合（来自缓存）
+func GetModelQuotaTypes(modelName string) []int {
 	GetPricing()
 
 	modelEnableGroupsLock.RLock()
 	quota, ok := modelQuotaTypeMap[modelName]
 	modelEnableGroupsLock.RUnlock()
 	if !ok {
-		return 0
+		return []int{}
 	}
-	return quota
+	return []int{quota}
 }