refactor(watcher): extract model summary functions to dedicated file

internal/watcher/diff/oauth_excluded.go

@@ -116,62 +116,3 @@ func SummarizeAmpModelMappings(mappings []config.AmpModelMapping) AmpModelMappin
 		count: len(entries),
 	}
 }
-
-type VertexModelsSummary struct {
-	hash  string
-	count int
-}
-
-type GeminiModelsSummary struct {
-	hash  string
-	count int
-}
-
-// SummarizeVertexModels hashes vertex-compatible models for change detection.
-func SummarizeVertexModels(models []config.VertexCompatModel) VertexModelsSummary {
-	if len(models) == 0 {
-		return VertexModelsSummary{}
-	}
-	names := make([]string, 0, len(models))
-	for _, m := range models {
-		name := strings.TrimSpace(m.Name)
-		alias := strings.TrimSpace(m.Alias)
-		if name == "" && alias == "" {
-			continue
-		}
-		if alias != "" {
-			name = alias
-		}
-		names = append(names, name)
-	}
-	if len(names) == 0 {
-		return VertexModelsSummary{}
-	}
-	sort.Strings(names)
-	sum := sha256.Sum256([]byte(strings.Join(names, "|")))
-	return VertexModelsSummary{
-		hash:  hex.EncodeToString(sum[:]),
-		count: len(names),
-	}
-}
-
-// SummarizeGeminiModels hashes Gemini model aliases for change detection.
-func SummarizeGeminiModels(models []config.GeminiModel) GeminiModelsSummary {
-	if len(models) == 0 {
-		return GeminiModelsSummary{}
-	}
-	keys := normalizeModelPairs(func(out func(key string)) {
-		for _, model := range models {
-			name := strings.TrimSpace(model.Name)
-			alias := strings.TrimSpace(model.Alias)
-			if name == "" && alias == "" {
-				continue
-			}
-			out(strings.ToLower(name) + "|" + strings.ToLower(alias))
-		}
-	})
-	return GeminiModelsSummary{
-		hash:  hashJoined(keys),
-		count: len(keys),
-	}
-}