refactor(launcher): split CLI flow into command modules

Isolate process-side effects behind adapter seams and keep wrapper behavior stable while improving command-level testability.

launcher/commands/context.ts

@@ -0,0 +1,12 @@
+import type { Args, LauncherJellyfinConfig } from '../types.js';
+import type { ProcessAdapter } from '../process-adapter.js';
+
+export interface LauncherCommandContext {
+  args: Args;
+  scriptPath: string;
+  scriptName: string;
+  mpvSocketPath: string;
+  appPath: string | null;
+  launcherJellyfinConfig: LauncherJellyfinConfig;
+  processAdapter: ProcessAdapter;
+}