Enhance tender recommendation caching and page refresh logic

- Introduced a new `RecommendedTendersPageCacheRefresher` interface to manage the asynchronous refresh of recommendation pages in Redis, improving cache management.
- Updated the `companyService` to support setting page cache languages and refreshing the recommended tenders page cache based on company IDs.
- Enhanced the `tenderService` to build and invalidate recommended tenders page caches, ensuring timely updates and efficient retrieval of cached recommendations.
- Added configuration options for recommendation page cache languages in the `AISummarizerConfig`, allowing for flexible language support.
- Implemented unit tests for the new caching logic and page refresh functionality, ensuring robust validation of the recommendation caching process.

This update significantly improves the efficiency and responsiveness of the tender recommendation service by integrating enhanced caching mechanisms and page refresh capabilities.

internal/company/recommendation_page_cache.go

@@ -0,0 +1,71 @@
+package company
+
+import (
+	"context"
+	"strings"
+)
+
+const recommendedTendersPageCacheKeyPrefix = "ai:recommendations:page:"
+
+func recommendedTendersPageCacheKey(companyID, language string) string {
+	return recommendedTendersPageCacheKeyPrefix +
+		strings.TrimSpace(companyID) + ":" +
+		strings.ToLower(strings.TrimSpace(language))
+}
+
+func (s *companyService) invalidateRecommendedTendersPageCache(ctx context.Context, companyID string) {
+	if s.redisClient == nil {
+		return
+	}
+
+	for _, language := range s.pageCacheLanguages {
+		lang := strings.ToLower(strings.TrimSpace(language))
+		if lang == "" {
+			continue
+		}
+		_ = s.redisClient.Del(ctx, recommendedTendersPageCacheKey(companyID, lang))
+	}
+}
+
+func (s *companyService) scheduleRecommendedTendersPageCacheRefresh(companyID string) {
+	if s.pageCacheRefresher == nil {
+		return
+	}
+	s.pageCacheRefresher.ScheduleRefreshRecommendedTendersPageCache(companyID)
+}
+
+// SetRecommendedTendersPageCacheRefresher wires async page-cache rebuilds from the tender service.
+func (s *companyService) SetRecommendedTendersPageCacheRefresher(refresher RecommendedTendersPageCacheRefresher) {
+	s.pageCacheRefresher = refresher
+}
+
+// SetPageCacheLanguages configures which language variants are invalidated in Redis.
+func (s *companyService) SetPageCacheLanguages(languages []string) {
+	s.pageCacheLanguages = normalizePageCacheLanguages("", languages)
+}
+
+func normalizePageCacheLanguages(defaultLanguage string, languages []string) []string {
+	seen := make(map[string]struct{})
+	out := make([]string, 0, len(languages)+1)
+
+	add := func(lang string) {
+		lang = strings.ToLower(strings.TrimSpace(lang))
+		if lang == "" {
+			return
+		}
+		if _, ok := seen[lang]; ok {
+			return
+		}
+		seen[lang] = struct{}{}
+		out = append(out, lang)
+	}
+
+	add(defaultLanguage)
+	for _, lang := range languages {
+		add(lang)
+	}
+	if len(out) == 0 {
+		out = append(out, "en")
+	}
+	return out
+}