Initial commit: ym-dl with yandex-music-api-go library migration

Migrate ym-dl from custom oapi-codegen Yandex Music API client to external
gitea.mrixs.me/Mrixs/yandex-music-api-go library with token-only authentication.

Key changes:
- Replace custom Yandex API client with yandexmusic library wrapper
- Token-based OAuth authentication only (no username/password fallback)
- SQLite storage index with JSON index migration path
- Extended ID3 tag support: genre, comment, lyrics, publisher, ISRC, copyright
- High-resolution album covers (1000x1000)
- Fixed album download check (requires all tracks, not just one)

internal/config/config_test.go

@@ -0,0 +1,199 @@
+package config
+
+import (
+	"os"
+	"testing"
+	"time"
+)
+
+func TestLoadValidConfig(t *testing.T) {
+	content := `
+yandex:
+  token: "test-token"
+artists:
+  - id: 12345
+storage:
+  path: "/data/music"
+  organize: true
+monitor:
+  interval: "24h"
+`
+	tmpfile, err := os.CreateTemp("", "config-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile.Name())
+
+	if _, err := tmpfile.WriteString(content); err != nil {
+		t.Fatal(err)
+	}
+	tmpfile.Close()
+
+	cfg, err := Load(tmpfile.Name())
+	if err != nil {
+		t.Fatalf("Load failed: %v", err)
+	}
+
+	if cfg.Yandex.Token != "test-token" {
+		t.Errorf("expected token 'test-token', got '%s'", cfg.Yandex.Token)
+	}
+	if len(cfg.Artists) != 1 || cfg.Artists[0].ID != 12345 {
+		t.Errorf("expected artist ID 12345, got %v", cfg.Artists)
+	}
+	if cfg.Storage.Path != "/data/music" {
+		t.Errorf("expected path '/data/music', got '%s'", cfg.Storage.Path)
+	}
+	if !cfg.Storage.Organize {
+		t.Error("expected organize=true")
+	}
+	interval, err := cfg.GetMonitorInterval()
+	if err != nil {
+		t.Fatalf("GetMonitorInterval failed: %v", err)
+	}
+	if interval != 24*time.Hour {
+		t.Errorf("expected 24h, got %v", interval)
+	}
+}
+
+func TestLoadConfigWithUsernamePassword(t *testing.T) {
+	content := `
+yandex:
+  username: "user"
+  password: "pass"
+artists:
+  - id: 1
+storage:
+  path: "/data"
+monitor:
+  interval: "1h"
+`
+	tmpfile, err := os.CreateTemp("", "config-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile.Name())
+
+	if _, err := tmpfile.WriteString(content); err != nil {
+		t.Fatal(err)
+	}
+	tmpfile.Close()
+
+	cfg, err := Load(tmpfile.Name())
+	if err != nil {
+		t.Fatalf("Load failed: %v", err)
+	}
+
+	if cfg.Yandex.Username != "user" || cfg.Yandex.Password != "pass" {
+		t.Errorf("expected username/password, got %v", cfg.Yandex)
+	}
+}
+
+func TestLoadConfigMissingAuth(t *testing.T) {
+	content := `
+yandex: {}
+artists:
+  - id: 1
+storage:
+  path: "/data"
+monitor:
+  interval: "1h"
+`
+	tmpfile, err := os.CreateTemp("", "config-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile.Name())
+
+	if _, err := tmpfile.WriteString(content); err != nil {
+		t.Fatal(err)
+	}
+	tmpfile.Close()
+
+	_, err = Load(tmpfile.Name())
+	if err == nil {
+		t.Error("expected error for missing auth")
+	}
+}
+
+func TestLoadConfigNoArtists(t *testing.T) {
+	content := `
+yandex:
+  token: "test"
+artists: []
+storage:
+  path: "/data"
+monitor:
+  interval: "1h"
+`
+	tmpfile, err := os.CreateTemp("", "config-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile.Name())
+
+	if _, err := tmpfile.WriteString(content); err != nil {
+		t.Fatal(err)
+	}
+	tmpfile.Close()
+
+	_, err = Load(tmpfile.Name())
+	if err == nil {
+		t.Error("expected error for no artists")
+	}
+}
+
+func TestLoadConfigInvalidInterval(t *testing.T) {
+	content := `
+yandex:
+  token: "test"
+artists:
+  - id: 1
+storage:
+  path: "/data"
+monitor:
+  interval: "invalid"
+`
+	tmpfile, err := os.CreateTemp("", "config-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile.Name())
+
+	if _, err := tmpfile.WriteString(content); err != nil {
+		t.Fatal(err)
+	}
+	tmpfile.Close()
+
+	_, err = Load(tmpfile.Name())
+	if err == nil {
+		t.Error("expected error for invalid interval")
+	}
+}
+
+func TestLoadConfigNegativeArtistID(t *testing.T) {
+	content := `
+yandex:
+  token: "test"
+artists:
+  - id: -1
+storage:
+  path: "/data"
+monitor:
+  interval: "1h"
+`
+	tmpfile, err := os.CreateTemp("", "config-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(tmpfile.Name())
+
+	if _, err := tmpfile.WriteString(content); err != nil {
+		t.Fatal(err)
+	}
+	tmpfile.Close()
+
+	_, err = Load(tmpfile.Name())
+	if err == nil {
+		t.Error("expected error for negative artist ID")
+	}
+}