feat: rename 'ZenithOS' => 'MontaukOS' and fix build system issues

programs/src/doom/Makefile

@@ -1,4 +1,4 @@
-# Makefile for DOOM (doomgeneric) on ZenithOS
+# Makefile for DOOM (doomgeneric) on MontaukOS
 # Copyright (c) 2025 Daniel Hammer
 
 MAKEFLAGS += -rR
@@ -153,7 +153,7 @@ DOOM_SRCS := \
     z_zone.c
 
 # Local source files
-LOCAL_SRCS := doomgeneric_zenith.c libc.c
+LOCAL_SRCS := doomgeneric_montauk.c libc.c
 
 # ---- Object files ----
 

programs/src/doom/doomgeneric_montauk.c

@@ -1,6 +1,6 @@
 /*
-    * doomgeneric_zenith.c
-    * DOOM platform implementation for ZenithOS (standalone window server client)
+    * doomgeneric_montauk.c
+    * DOOM platform implementation for MontaukOS (standalone window server client)
     * Copyright (c) 2025 Daniel Hammer
 */
 
@@ -66,7 +66,7 @@ static inline long _zos_syscall4(long nr, long a1, long a2, long a3, long a4) {
 #define SYS_WINPRESENT      56
 #define SYS_WINPOLL         57
 
-/* Window server structs (must match Zenith::WinCreateResult and Zenith::WinEvent) */
+/* Window server structs (must match Montauk::WinCreateResult and Montauk::WinEvent) */
 struct WinCreateResult {
     int      id;        /* -1 on failure */
     unsigned _pad;

programs/src/doom/libc.c

@@ -1,6 +1,6 @@
 /*
     * libc.c
-    * Minimal C standard library for ZenithOS userspace (DOOM port)
+    * Minimal C standard library for MontaukOS userspace (DOOM port)
     * Copyright (c) 2025 Daniel Hammer
 */