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/metadata/client.go

@@ -0,0 +1,56 @@
+package metadata
+
+import (
+	"context"
+	"strings"
+
+	pb "github.com/fujin/music-agregator/pkg/metadatapb/metadata/v1"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+type Client struct {
+	conn   *grpc.ClientConn
+	client pb.MetadataServiceClient
+}
+
+func NewClient(endpoint string) (*Client, error) {
+	endpoint = strings.TrimPrefix(endpoint, "http://")
+	endpoint = strings.TrimPrefix(endpoint, "https://")
+
+	conn, err := grpc.NewClient(endpoint, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		return nil, err
+	}
+
+	return &Client{
+		conn:   conn,
+		client: pb.NewMetadataServiceClient(conn),
+	}, nil
+}
+
+func (c *Client) Close() error {
+	return c.conn.Close()
+}
+
+func (c *Client) SearchArtists(ctx context.Context, query string, limit, offset int32) (*pb.SearchArtistsResponse, error) {
+	return c.client.SearchArtists(ctx, &pb.SearchArtistsRequest{
+		Query:  query,
+		Limit:  limit,
+		Offset: offset,
+	})
+}
+
+func (c *Client) GetArtist(ctx context.Context, id string) (*pb.Artist, error) {
+	return c.client.GetArtist(ctx, &pb.GetArtistRequest{
+		Identifier: &pb.GetArtistRequest_Id{Id: id},
+	})
+}
+
+func (c *Client) GetArtistAlbums(ctx context.Context, artistID string, limit, offset int32) (*pb.GetArtistAlbumsResponse, error) {
+	return c.client.GetArtistAlbums(ctx, &pb.GetArtistAlbumsRequest{
+		ArtistId: artistID,
+		Limit:    limit,
+		Offset:   offset,
+	})
+}