refactor(launcher): split config parser and CLI builder

Decompose launcher/config.ts into focused domain parser and CLI normalization modules to reduce refactor risk while preserving command behavior. Align Jellyfin launcher config with session-based auth by dropping config token/userId dependency.

launcher/config/shared-config-reader.ts

@@ -0,0 +1,25 @@
+import fs from 'node:fs';
+import os from 'node:os';
+import { parse as parseJsonc } from 'jsonc-parser';
+import { resolveConfigFilePath } from '../../src/config/path-resolution.js';
+
+export function resolveLauncherMainConfigPath(): string {
+  return resolveConfigFilePath({
+    xdgConfigHome: process.env.XDG_CONFIG_HOME,
+    homeDir: os.homedir(),
+    existsSync: fs.existsSync,
+  });
+}
+
+export function readLauncherMainConfigObject(): Record<string, unknown> | null {
+  const configPath = resolveLauncherMainConfigPath();
+  if (!fs.existsSync(configPath)) return null;
+  try {
+    const data = fs.readFileSync(configPath, 'utf8');
+    const parsed = configPath.endsWith('.jsonc') ? parseJsonc(data) : JSON.parse(data);
+    if (!parsed || typeof parsed !== 'object') return null;
+    return parsed as Record<string, unknown>;
+  } catch {
+    return null;
+  }
+}