GUI: add on-screen toasts and atomic config writes

- Toast queue drawn in the top-right by the overlay, independent of the GUI
  being open. Info/warn/error colors and 6/9/12 s lifetimes; timers start on
  the first painted frame so startup messages are not missed.
- Queue a load toast after install_menu, plus warnings/errors for missing
  modules/interfaces/netvars, input hooks, fonts, ISurface, server datamap,
  and spread seed support.
- Toast on config reload, reset, bind/unbind and config save failure.
- Config saves now write `config.tmp`, flush, then rename it over the real
  file; failures leave the previous config intact.
- config_load reports whether a file was found so Reload can distinguish a
  successful reload from a missing file.
- Update CONTEXT and ISURFACE_STATUS for the single GUI, toasts and atomic
  config writes.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/cinput.cpp b/src/cinput.cpp
index ad7face..f466c53 100644
--- a/src/cinput.cpp
+++ b/src/cinput.cpp
@@ -228,7 +228,8 @@ bool find_input_global() {
       logf("CInput* = %#lx (ptr var %#lx, vfunc[3] %#lx)", (unsigned long)input,
            (unsigned long)var, (unsigned long)f3);
       g_input = input;
-      install_input_hook();
+      if (!install_input_hook())
+        toastf(TOAST_ERROR, "Input vtable hook failed; features disabled");
       return true;
     }
   }