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, 7 insertions, 0 deletions

diff --git a/CONTEXT.md b/CONTEXT.md
index 5e0e4b2..78f7c75 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -116,6 +116,11 @@ vocabulary / decisions.
   and ESP/FOV circle/speed graph keep drawing. No invulnerability.
 - **Native cursor**: on open, leave SDL relative-mouse mode and show the OS
   cursor; restore on close. Absolute mouse coordinates are used.
+- **Toast**: transient top-right notification drawn by the overlay even when
+  the GUI is closed. Info/warn/error colors; lifetimes 6/9/12 s. Toasts queued
+  before the first paint (load errors) start their timer when first drawn.
+  Used for the load message, config problems, missing interfaces/netvars,
+  bind changes, Reload and Reset.
 - **Bind capture**: click Bind, press a key or any mouse button; Esc cancels
   capture but does not close the GUI; the small x clears the bind (None =
   always-on). Insert is reserved for the GUI.
@@ -134,6 +139,8 @@ vocabulary / decisions.
   `x`, `y`, `category` and an `expanded` bitmask (card index order). Every
   feature now persists an `active` and `bind` pair, including movement, melee
   and spread.
+- Config writes are atomic: `config.tmp` is written and flushed, then
+  `rename()`d over the real file. A failed write raises an error toast.
 
 
 ## Bones / ESP