clean: just handle auth as configure handles the rest of the flow

auditui/auth.py

@@ -1,6 +1,5 @@
 """Authentication helpers for the Auditui app."""
 
-from getpass import getpass
 from pathlib import Path
 from typing import Tuple
 
@@ -13,30 +12,14 @@ def authenticate(
     auth_path: Path = AUTH_PATH,
 ) -> Tuple[audible.Authenticator, audible.Client]:
     """Authenticate with Audible and return authenticator and client."""
-    auth_path.parent.mkdir(parents=True, exist_ok=True)
+    if not auth_path.exists():
+        raise FileNotFoundError(
+            "Authentication file not found. Please run 'auditui configure' to set up authentication.")
 
-    if auth_path.exists():
-        try:
-            authenticator = audible.Authenticator.from_file(str(auth_path))
-            audible_client = audible.Client(auth=authenticator)
-            return authenticator, audible_client
-        except (OSError, ValueError, KeyError) as exc:
-            print(f"Failed to load existing auth: {exc}")
-            print("Please re-authenticate.")
-
-    print("Please authenticate with your Audible account.")
-
-    email = input("\nEmail: ")
-    password = getpass("Password: ")
-    marketplace = input(
-        "Marketplace locale (default: US): ").strip().upper() or "US"
-
-    authenticator = audible.Authenticator.from_login(
-        username=email, password=password, locale=marketplace
-    )
-
-    auth_path.parent.mkdir(parents=True, exist_ok=True)
-    authenticator.to_file(str(auth_path))
-    print("Authentication successful!")
-    audible_client = audible.Client(auth=authenticator)
-    return authenticator, audible_client
+    try:
+        authenticator = audible.Authenticator.from_file(str(auth_path))
+        audible_client = audible.Client(auth=authenticator)
+        return authenticator, audible_client
+    except (OSError, ValueError, KeyError) as exc:
+        raise ValueError(
+            f"Failed to load existing authentication: {exc}") from exc