merge: integrate feature/login and resolve config conflict

config.txt

@@ -1 +1 @@
-mode=main
+mode=login-integrated

src/login_module.c

@@ -0,0 +1,6 @@
+/* Login feature source file for Git branch practice. */
+
+int Login_CheckCredentials(const char *user, const char *password)
+{
+    return (user != 0) && (password != 0);
+}