refactor: rewrite project from Rust to Go

- Replace Axum with Chi router
- Replace sqlx with pgx for PostgreSQL
- Replace tonic/prost with grpc-go
- Replace tracing with zerolog
- Update flake.nix for Go build with protoc generation
- Preserve all existing endpoints and functionality

Stack: Chi, pgx, grpc-go, zerolog, yaml.v3

internal/services/indexer.go

@@ -0,0 +1,84 @@
+package services
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/fujin/music-agregator/internal/config"
+	"github.com/fujin/music-agregator/internal/indexer"
+)
+
+type IndexerService struct {
+	indexers []*indexer.TorznabIndexer
+}
+
+type IndexerInfo struct {
+	Name    string `json:"name"`
+	URL     string `json:"url"`
+	Healthy bool   `json:"healthy"`
+}
+
+func NewIndexerService(configs []config.IndexerConfig) (*IndexerService, error) {
+	var indexers []*indexer.TorznabIndexer
+
+	for _, cfg := range configs {
+		url := buildTorznabURL(cfg)
+		idx, err := indexer.NewTorznabIndexer(cfg.Name, url, cfg.APIKey)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create indexer %s: %w", cfg.Name, err)
+		}
+		indexers = append(indexers, idx)
+	}
+
+	return &IndexerService{indexers: indexers}, nil
+}
+
+func buildTorznabURL(cfg config.IndexerConfig) string {
+	url := strings.TrimRight(cfg.URL, "/")
+
+	switch cfg.IndexerType {
+	case config.IndexerTypeJackett:
+		if !strings.Contains(url, "/api/") {
+			url = fmt.Sprintf("%s/api/v2.0/indexers/all/results/torznab", url)
+		}
+	case config.IndexerTypeProwlarr:
+		if !strings.Contains(url, "/api/") {
+			url = fmt.Sprintf("%s/api/v1/indexer/all/newznab", url)
+		}
+	}
+
+	return url
+}
+
+func (s *IndexerService) Search(ctx context.Context, criteria *indexer.MusicSearchCriteria, indexerName *string) ([]indexer.SearchResult, error) {
+	var results []indexer.SearchResult
+
+	for _, idx := range s.indexers {
+		if indexerName != nil && idx.Name() != *indexerName {
+			continue
+		}
+
+		r, err := idx.Search(ctx, criteria)
+		if err != nil {
+			continue
+		}
+		results = append(results, r...)
+	}
+
+	return results, nil
+}
+
+func (s *IndexerService) GetIndexers(ctx context.Context) []IndexerInfo {
+	var infos []IndexerInfo
+
+	for _, idx := range s.indexers {
+		healthy := idx.TestConnection(ctx) == nil
+		infos = append(infos, IndexerInfo{
+			Name:    idx.Name(),
+			Healthy: healthy,
+		})
+	}
+
+	return infos
+}