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/cmd/root.go

@@ -66,6 +66,8 @@ Source:         https://github.com/torrentclaw/torrentclaw-cli`,
 	initCmd.GroupID = "start"
 	configCmd := newConfigCmd()
 	configCmd.GroupID = "start"
+	migrateCmd := newMigrateCmd()
+	migrateCmd.GroupID = "start"
 
 	// Search & Discovery
 	searchCmd := newSearchCmd()
@@ -109,10 +111,15 @@ Source:         https://github.com/torrentclaw/torrentclaw-cli`,
 	completionCmd := newCompletionCmd()
 	completionCmd.GroupID = "system"
 
+	// Library
+	scanCmd := newScanCmd()
+	scanCmd.GroupID = "search"
+
 	rootCmd.AddCommand(
 		// Getting Started
 		initCmd,
 		configCmd,
+		migrateCmd,
 		// Search & Discovery
 		searchCmd,
 		inspectCmd,
@@ -134,11 +141,12 @@ Source:         https://github.com/torrentclaw/torrentclaw-cli`,
 		selfUpdateCmd,
 		versionCmd,
 		completionCmd,
+		// Library
+		scanCmd,
 		// Stubs for future commands
 		newStubCmd("upgrade", "Find a better version of a torrent"),
 		newStubCmd("moreseed", "Find same quality with more seeders"),
 		newStubCmd("compare", "Compare two torrents side by side"),
-		newStubCmd("scan", "Scan your media library for upgrades"),
 		newStubCmd("add", "Search and add torrents to your client"),
 		newStubCmd("monitor", "Watch for new episodes of a series"),
 		newStubCmd("open", "Open content in the browser"),