feat: add migrate command, media server detection, and debrid auto-config

- Migration wizard from Sonarr/Radarr/Prowlarr (unarr migrate) [pre-beta]
  - Auto-detect instances via Docker, config files, port scan, Prowlarr
  - Import wanted list (monitored+missing movies/series)
  - Import download history and blocklist to avoid re-downloading
  - Extract debrid tokens from *arr download clients
  - Quality profile mapping to preferred_quality config
  - DISTINCT ON PostgreSQL query for optimal torrent selection
  - JSON export with --dry-run --json (text to stderr, JSON to stdout)
- Media server detection (Plex/Jellyfin/Emby) in unarr init
  - Detects library paths and offers them as download directory options
- Debrid auto-configuration in unarr init
  - Scans *arr instances for debrid tokens
  - Validates and saves via API if user confirms
- New preferred_quality setting in config (2160p/1080p/720p)
- Library scan command (unarr scan) with ffprobe metadata extraction

internal/arr/discovery_test.go

@@ -0,0 +1,84 @@
+package arr
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestParseConfigXML(t *testing.T) {
+	xml := `<Config>
+		<Port>8989</Port>
+		<ApiKey>abc123def456</ApiKey>
+		<UrlBase>/sonarr</UrlBase>
+	</Config>`
+
+	port, apiKey, urlBase := parseConfigXML(strings.NewReader(xml))
+	if port != "8989" {
+		t.Errorf("port = %q, want 8989", port)
+	}
+	if apiKey != "abc123def456" {
+		t.Errorf("apiKey = %q, want abc123def456", apiKey)
+	}
+	if urlBase != "/sonarr" {
+		t.Errorf("urlBase = %q, want /sonarr", urlBase)
+	}
+}
+
+func TestParseConfigXML_Minimal(t *testing.T) {
+	xml := `<Config><Port>7878</Port><ApiKey>key</ApiKey></Config>`
+
+	port, apiKey, urlBase := parseConfigXML(strings.NewReader(xml))
+	if port != "7878" || apiKey != "key" || urlBase != "" {
+		t.Errorf("got port=%q apiKey=%q urlBase=%q", port, apiKey, urlBase)
+	}
+}
+
+func TestParseConfigXML_Invalid(t *testing.T) {
+	port, apiKey, _ := parseConfigXML(strings.NewReader("not xml"))
+	if port != "" || apiKey != "" {
+		t.Errorf("invalid XML should return empty values")
+	}
+}
+
+func TestExtractHostPort(t *testing.T) {
+	tests := []struct {
+		ports     string
+		container string
+		want      string
+	}{
+		{"0.0.0.0:8989->8989/tcp", "8989", "8989"},
+		{"0.0.0.0:9090->8989/tcp, :::9090->8989/tcp", "8989", "9090"},
+		{"0.0.0.0:7878->7878/tcp", "7878", "7878"},
+		{"", "8989", ""},
+		{"0.0.0.0:3000->3000/tcp", "8989", ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.ports, func(t *testing.T) {
+			got := extractHostPort(tt.ports, tt.container)
+			if got != tt.want {
+				t.Errorf("extractHostPort(%q, %q) = %q, want %q", tt.ports, tt.container, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestDetectApp(t *testing.T) {
+	tests := []struct {
+		image string
+		want  string
+	}{
+		{"linuxserver/sonarr:latest", "sonarr"},
+		{"hotio/radarr", "radarr"},
+		{"ghcr.io/linuxserver/prowlarr:develop", "prowlarr"},
+		{"nginx:latest", ""},
+		{"postgres:16", ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.image, func(t *testing.T) {
+			got := detectApp(tt.image)
+			if got != tt.want {
+				t.Errorf("detectApp(%q) = %q, want %q", tt.image, got, tt.want)
+			}
+		})
+	}
+}