feat(thinking): add HasLevel and MapToClaudeEffort functions for adaptive thinking support

internal/thinking/provider/codex/apply.go

@@ -7,8 +7,6 @@
 package codex
 
 import (
-	"strings"
-
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/thinking"
 	"github.com/tidwall/gjson"
@@ -68,7 +66,7 @@ func (a *Applier) Apply(body []byte, config thinking.ThinkingConfig, modelInfo *
 	effort := ""
 	support := modelInfo.Thinking
 	if config.Budget == 0 {
-		if support.ZeroAllowed || hasLevel(support.Levels, string(thinking.LevelNone)) {
+		if support.ZeroAllowed || thinking.HasLevel(support.Levels, string(thinking.LevelNone)) {
 			effort = string(thinking.LevelNone)
 		}
 	}
@@ -120,12 +118,3 @@ func applyCompatibleCodex(body []byte, config thinking.ThinkingConfig) ([]byte,
 	result, _ := sjson.SetBytes(body, "reasoning.effort", effort)
 	return result, nil
 }
-
-func hasLevel(levels []string, target string) bool {
-	for _, level := range levels {
-		if strings.EqualFold(strings.TrimSpace(level), target) {
-			return true
-		}
-	}
-	return false
-}