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/library/mediainfo/lang.go

@@ -0,0 +1,115 @@
+package mediainfo
+
+import (
+	"sort"
+	"strings"
+)
+
+// langNormalize maps ISO 639-2/B, 639-2/T, 639-1 codes, and full English
+// language names (as returned by some ffprobe metadata) to ISO 639-1.
+var langNormalize = map[string]string{
+	// ISO codes
+	"eng": "en", "en": "en",
+	"spa": "es", "es": "es",
+	"fre": "fr", "fra": "fr", "fr": "fr",
+	"ger": "de", "deu": "de", "de": "de",
+	"ita": "it", "it": "it",
+	"por": "pt", "pt": "pt",
+	"rus": "ru", "ru": "ru",
+	"jpn": "ja", "ja": "ja",
+	"kor": "ko", "ko": "ko",
+	"chi": "zh", "zho": "zh", "zh": "zh",
+	"hin": "hi", "hi": "hi",
+	"ara": "ar", "ar": "ar",
+	"dut": "nl", "nld": "nl", "nl": "nl",
+	"pol": "pl", "pl": "pl",
+	"tur": "tr", "tr": "tr",
+	"swe": "sv", "sv": "sv",
+	"nor": "no", "nob": "no", "nno": "no", "no": "no",
+	"dan": "da", "da": "da",
+	"fin": "fi", "fi": "fi",
+	"cze": "cs", "ces": "cs", "cs": "cs",
+	"hun": "hu", "hu": "hu",
+	"rum": "ro", "ron": "ro", "ro": "ro",
+	"gre": "el", "ell": "el", "el": "el",
+	"tha": "th", "th": "th",
+	"vie": "vi", "vi": "vi",
+	"ind": "id", "id": "id",
+	"heb": "he", "he": "he",
+	"ukr": "uk", "uk": "uk",
+	"cat": "ca", "ca": "ca",
+	"bul": "bg", "bg": "bg",
+	"hrv": "hr", "hr": "hr",
+	"srp": "sr", "sr": "sr",
+	"slv": "sl", "sl": "sl",
+	"lit": "lt", "lt": "lt",
+	"lav": "lv", "lv": "lv",
+	"est": "et", "et": "et",
+	"per": "fa", "fas": "fa", "fa": "fa",
+	"may": "ms", "msa": "ms", "ms": "ms",
+	"tgl": "tl", "tl": "tl",
+	"tam": "ta", "ta": "ta",
+	"tel": "te", "te": "te",
+	"ben": "bn", "bn": "bn",
+	"urd": "ur", "ur": "ur",
+	"geo": "ka", "kat": "ka", "ka": "ka",
+	"arm": "hy", "hye": "hy", "hy": "hy",
+	"alb": "sq", "sqi": "sq", "sq": "sq",
+	"mac": "mk", "mkd": "mk", "mk": "mk",
+	"ice": "is", "isl": "is", "is": "is",
+	"glg": "gl", "gl": "gl",
+	"baq": "eu", "eus": "eu", "eu": "eu",
+	"wel": "cy", "cym": "cy", "cy": "cy",
+	"gle": "ga", "ga": "ga",
+	"mlt": "mt", "mt": "mt",
+	"swa": "sw", "sw": "sw",
+	"afr": "af", "af": "af",
+	"lat": "la", "la": "la",
+
+	// Full English names (ffprobe sometimes returns these instead of codes)
+	"english": "en", "spanish": "es", "french": "fr", "german": "de",
+	"italian": "it", "portuguese": "pt", "russian": "ru", "japanese": "ja",
+	"korean": "ko", "chinese": "zh", "hindi": "hi", "arabic": "ar",
+	"dutch": "nl", "polish": "pl", "turkish": "tr", "swedish": "sv",
+	"norwegian": "no", "danish": "da", "finnish": "fi", "czech": "cs",
+	"hungarian": "hu", "romanian": "ro", "greek": "el", "thai": "th",
+	"vietnamese": "vi", "indonesian": "id", "hebrew": "he", "ukrainian": "uk",
+	"catalan": "ca", "bulgarian": "bg", "croatian": "hr", "serbian": "sr",
+	"slovenian": "sl", "lithuanian": "lt", "latvian": "lv", "estonian": "et",
+	"persian": "fa", "malay": "ms", "tagalog": "tl", "tamil": "ta",
+	"telugu": "te", "bengali": "bn", "urdu": "ur", "georgian": "ka",
+	"armenian": "hy", "albanian": "sq", "macedonian": "mk", "icelandic": "is",
+	"galician": "gl", "basque": "eu", "welsh": "cy", "irish": "ga",
+	"maltese": "mt", "swahili": "sw", "afrikaans": "af", "latin": "la",
+}
+
+// NormalizeLang converts a language code to ISO 639-1.
+// Returns "und" for empty input, the input lowercased if no mapping is found.
+func NormalizeLang(raw string) string {
+	if raw == "" {
+		return "und"
+	}
+	lower := strings.ToLower(raw)
+	if mapped, ok := langNormalize[lower]; ok {
+		return mapped
+	}
+	return lower
+}
+
+// ComputeLanguages extracts unique ISO 639-1 language codes from audio tracks.
+func ComputeLanguages(audioTracks []AudioTrack) []string {
+	seen := make(map[string]struct{})
+	for _, t := range audioTracks {
+		lang := t.Lang
+		if lang != "" && lang != "und" && len(lang) <= 3 {
+			seen[lang] = struct{}{}
+		}
+	}
+
+	result := make([]string, 0, len(seen))
+	for l := range seen {
+		result = append(result, l)
+	}
+	sort.Strings(result)
+	return result
+}