feat: expand user mode, add DOOM game, add manpages

kernel/src/Terminal/Terminal.hpp

@@ -165,4 +165,10 @@ namespace Kt
     };
 };
 
-extern Kt::KernelErrorStream kerr;
+extern Kt::KernelErrorStream kerr;
+
+// Forward-declare flanterm context for syscall access
+struct flanterm_context;
+namespace Kt {
+    extern flanterm_context *ctx;
+}