feat: unify system status codes

programs/src/display/main.cpp

@@ -500,7 +500,7 @@ static void apply_changes() {
     if (g_driver_available && g_selected_mode != g_info.currentMode) {
         int result = montauk::display_set_mode(g_selected_mode);
         if (result < 0) {
-            set_status(result == -2
+            set_status(result == montauk::UnsupportedOp
                 ? "Mode needs unsupported display-link training"
                 : "Mode change failed; previous mode restored");
             refresh_state(true);

programs/src/login/login_shutdown.cpp

@@ -262,7 +262,7 @@ void perform_graceful_shutdown(LoginState* ls, int action) {
     // A successful power-control syscall never returns.  If it does return,
     // keep the trusted supervisor alive and make the authorization failure
     // visible instead of falling through an unreachable-code assumption.
-    show_stage(ls, heading, rc == montauk::abi::SYS_ERR_PERMISSION
+    show_stage(ls, heading, rc == montauk::CapabilityDenied
         ? "Power control permission denied."
         : "Power control failed.");
     for (;;) montauk::sleep_ms(1000);

programs/src/reset/main.cpp

@@ -9,7 +9,7 @@
 extern "C" void _start() {
     montauk::print("Rebooting...\n");
     int rc = montauk::reset();
-    if (rc == montauk::abi::SYS_ERR_PERMISSION)
+    if (rc == montauk::CapabilityDenied)
         montauk::print("reset: permission denied\n");
     else
         montauk::print("reset: reboot failed\n");

programs/src/shell/main.cpp

@@ -194,7 +194,7 @@ static int process_command(const char* line) {
             : montauk::abi::POWER_REQ_SHUTDOWN;
         int rc = montauk::power_request(action);
         if (rc == 0) montauk::exit(0);
-        montauk::print(rc == montauk::abi::SYS_ERR_PERMISSION
+        montauk::print(rc == montauk::CapabilityDenied
             ? "power: permission denied\n"
             : "power: request failed\n");
         return 1;
@@ -202,7 +202,7 @@ static int process_command(const char* line) {
 
     if (streq(cmd, "suspend")) {
         int rc = montauk::suspend();
-        if (rc == montauk::abi::SYS_ERR_PERMISSION)
+        if (rc == montauk::CapabilityDenied)
             montauk::print("suspend: permission denied\n");
         return rc == 0 ? 0 : 1;
     }