refactor(main): split main.ts into focused runtime modules (#123)

src/main/password-store-args.ts

@@ -0,0 +1,40 @@
+const PASSWORD_STORE_ARG = '--password-store';
+const DEFAULT_LINUX_PASSWORD_STORE = 'gnome-libsecret';
+
+export function getPasswordStoreArg(argv: string[]): string | null {
+  let resolved: string | null = null;
+  for (let i = 0; i < argv.length; i += 1) {
+    const arg = argv[i];
+    if (!arg?.startsWith(PASSWORD_STORE_ARG)) {
+      continue;
+    }
+
+    if (arg === PASSWORD_STORE_ARG) {
+      const value = argv[i + 1];
+      const trimmed = value?.trim();
+      if (trimmed && !trimmed.startsWith('--')) {
+        resolved = trimmed;
+        i += 1;
+      }
+      continue;
+    }
+
+    const [prefix, value] = arg.split('=', 2);
+    if (prefix === PASSWORD_STORE_ARG && value && value.trim().length > 0) {
+      resolved = value.trim();
+    }
+  }
+  return resolved;
+}
+
+export function normalizePasswordStoreArg(value: string): string {
+  const normalized = value.trim();
+  if (normalized.toLowerCase() === 'gnome') {
+    return DEFAULT_LINUX_PASSWORD_STORE;
+  }
+  return normalized;
+}
+
+export function getDefaultPasswordStore(): string {
+  return DEFAULT_LINUX_PASSWORD_STORE;
+}