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/config/config.go

@@ -0,0 +1,92 @@
+package config
+
+import (
+	"fmt"
+	"os"
+
+	"gopkg.in/yaml.v3"
+)
+
+type Config struct {
+	App      AppConfig       `yaml:"app"`
+	Database DatabaseConfig  `yaml:"database"`
+	Metadata MetadataConfig  `yaml:"metadata"`
+	Indexers []IndexerConfig `yaml:"indexers"`
+	Torrent  TorrentConfig   `yaml:"torrent"`
+}
+
+type AppConfig struct {
+	Port int `yaml:"port"`
+}
+
+type DatabaseConfig struct {
+	URL string `yaml:"url"`
+}
+
+type MetadataConfig struct {
+	Endpoint string `yaml:"endpoint"`
+}
+
+type IndexerType string
+
+const (
+	IndexerTypeJackett  IndexerType = "jackett"
+	IndexerTypeProwlarr IndexerType = "prowlarr"
+	IndexerTypeTorznab  IndexerType = "torznab"
+)
+
+type IndexerConfig struct {
+	Name        string      `yaml:"name"`
+	IndexerType IndexerType `yaml:"indexer_type"`
+	URL         string      `yaml:"url"`
+	APIKey      string      `yaml:"api_key"`
+}
+
+type TorrentClientType string
+
+const (
+	TorrentClientQBittorrent TorrentClientType = "qbittorrent"
+	TorrentClientStub        TorrentClientType = "stub"
+	TorrentClientNone        TorrentClientType = "none"
+)
+
+type TorrentConfig struct {
+	ClientType TorrentClientType `yaml:"client_type"`
+	URL        string            `yaml:"url,omitempty"`
+	Username   string            `yaml:"username,omitempty"`
+	Password   string            `yaml:"password,omitempty"`
+	LogPath    string            `yaml:"log_path,omitempty"`
+	SavePath   string            `yaml:"save_path,omitempty"`
+}
+
+func Load(path string) (*Config, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read config file: %w", err)
+	}
+
+	var cfg Config
+	if err := yaml.Unmarshal(data, &cfg); err != nil {
+		return nil, fmt.Errorf("failed to parse config: %w", err)
+	}
+
+	if cfg.App.Port == 0 {
+		cfg.App.Port = 3000
+	}
+
+	for i := range cfg.Indexers {
+		if cfg.Indexers[i].IndexerType == "" {
+			cfg.Indexers[i].IndexerType = IndexerTypeJackett
+		}
+	}
+
+	if cfg.Torrent.ClientType == "" {
+		cfg.Torrent.ClientType = TorrentClientNone
+	}
+
+	if cfg.Torrent.SavePath == "" {
+		cfg.Torrent.SavePath = "/tmp/downloads"
+	}
+
+	return &cfg, nil
+}