Reduce Gemini fallback noise and restore result volume

backend/services/ranker.go

@@ -87,7 +87,7 @@ func RankSearchResults(query string, results []SearchResult) []SearchResult {
 }
 
 func GeminiCandidateLimit(total int) int {
-	return min(total, 12)
+	return min(total, 16)
 }
 
 func EvaluateAllCandidatesWithGemini(service *GeminiService, query string, ranked []SearchResult) ([]AIRecommendation, GeminiBatchStats, error) {
@@ -314,9 +314,9 @@ func MergeRecommendations(recommended []AIRecommendation, ranked []SearchResult,
 		merged = append(merged, item)
 	}
 
-	if len(merged) < min(6, limit) {
+	if len(merged) < min(12, limit) {
 		for _, item := range ranked {
-			if len(merged) >= min(6, limit) || item.Link == "" || seen[item.Link] {
+			if len(merged) >= min(12, limit) || item.Link == "" || seen[item.Link] {
 				continue
 			}
 			if strings.TrimSpace(item.ThumbnailURL) == "" && strings.TrimSpace(item.PreviewVideoURL) == "" {
@@ -330,7 +330,7 @@ func MergeRecommendations(recommended []AIRecommendation, ranked []SearchResult,
 				ThumbnailURL:    item.ThumbnailURL,
 				PreviewVideoURL: item.PreviewVideoURL,
 				Source:          item.Source,
-				Reason:          GeminiFallbackReason,
+				Reason:          "Gemini 검토가 부족해 편집용 후보로 추가된 결과입니다.",
 				Recommended:     false,
 			})
 		}