feat: print complete default configuration from CLI

Sources/CLI/PlayerCommand.swift

@@ -2,6 +2,7 @@ import Foundation
 
 enum PlayerCommand {
     case help
+    case printDefaultConfig
     case launch(URL?, newInstance: Bool, noConfig: Bool)
 
     static let usage = """
@@ -9,6 +10,7 @@ enum PlayerCommand {
            terebi [--new-instance] [--no-config] --url YOUTUBE_URL
            terebi [--new-instance] [--no-config] -- FILE
            terebi --help
+           terebi --print-default-config
 
     Open one local media file or YouTube video and start playback, resuming saved
     video progress when available. With no arguments, open or activate the player.
@@ -19,6 +21,7 @@ enum PlayerCommand {
       --url URL      Open a YouTube video URL.
       --             Treat the following argument as a filename, even with a leading '-'.
       -h, --help     Show this help without launching the player.
+      --print-default-config Print the complete built-in TOML without launching.
 
     Reuses the running player unless --new-instance is supplied before the media
     arguments. The command exits once macOS accepts the launch; playback and
@@ -41,6 +44,7 @@ enum PlayerCommand {
         }
         if inputs.isEmpty { return .launch(nil, newInstance: newInstance, noConfig: noConfig) }
         if inputs == ["--help"] || inputs == ["-h"] { return .help }
+        if inputs == ["--print-default-config"] { return .printDefaultConfig }
         if inputs.first == "--url" {
             guard inputs.count == 2 else { throw ArgumentError("--url requires exactly one YouTube URL.") }
             return .launch(try YouTubeResolver.validateURL(inputs[1]), newInstance: newInstance, noConfig: noConfig)

Sources/CLI/TerebiCLI.swift

@@ -15,6 +15,8 @@ enum TerebiCLI {
         switch command {
         case .help:
             print(PlayerCommand.usage)
+        case .printDefaultConfig:
+            print(PlayerConfiguration.defaultTOML, terminator: "")
         case .launch(let url, let newInstance, let noConfig):
             let configURL = PlayerConfiguration.fileURL(environment: ProcessInfo.processInfo.environment,
                 homeDirectory: FileManager.default.homeDirectoryForCurrentUser)