feat: load optional XDG TOML configuration with session overrides

Sources/CLI/TerebiCLI.swift

@@ -1,5 +1,6 @@
 import AppKit
 import Darwin
+import TerebiConfiguration
 
 @main
 @MainActor
@@ -14,7 +15,16 @@ enum TerebiCLI {
         switch command {
         case .help:
             print(PlayerCommand.usage)
-        case .launch(let url, let newInstance):
+        case .launch(let url, let newInstance, let noConfig):
+            let configURL = PlayerConfiguration.fileURL(environment: ProcessInfo.processInfo.environment,
+                homeDirectory: FileManager.default.homeDirectoryForCurrentUser)
+            if !noConfig {
+                do {
+                    _ = try PlayerConfiguration.load(from: configURL)
+                } catch {
+                    fail(error.localizedDescription, code: 78)
+                }
+            }
             guard let executable = Bundle.main.executableURL else {
                 fail("Could not locate the CLI executable.", code: 69)
             }
@@ -25,8 +35,10 @@ enum TerebiCLI {
             }
             let configuration = NSWorkspace.OpenConfiguration()
             configuration.createsNewApplicationInstance = newInstance
+            // LaunchServices does not inherit the invoking shell's XDG environment.
+            configuration.arguments = noConfig ? ["--no-config"] : ["--config-file", configURL.absoluteString]
             if newInstance, let url {
-                configuration.arguments = ["--open-media", url.absoluteString]
+                configuration.arguments += ["--open-media", url.absoluteString]
             }
             do {
                 // Launch an application, not a document, so SwiftUI creates its singleton window.