niri: Mod+G gamemode toggle; drop dead VRR rules

The eDP-1 panel has no VRR, so the three variable-refresh-rate rules
(including the incorrect is-focused=true one) were no-ops. Removed;
left a breadcrumb comment for a future external VRR monitor.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

niri/config.kdl

@@ -56,6 +56,7 @@ binds {
     Mod+D { spawn "wofi" "--show" "drun"; }
     Mod+E { spawn "thunar"; }
     Mod+Shift+B { spawn "waybar-restart"; }
+    Mod+G { spawn "gamemode-session" "toggle"; }
 
     Mod+H { focus-column-left; }
     Mod+L { focus-column-right; }
@@ -107,7 +108,9 @@ binds {
 
 // ── Window Rules ─────────────────────────────────────────────────────────────
 
-// Fullscreen games: no border, open fullscreen, enable VRR
+// Fullscreen games: no border, open fullscreen.
+// (Re-add `variable-refresh-rate true` here if a VRR-capable external
+//  monitor is ever attached — the internal eDP-1 panel has no VRR.)
 window-rule {
     match app-id="steam_app_"
     open-fullscreen true
@@ -117,13 +120,6 @@ window-rule {
     focus-ring {
         off
     }
-    variable-refresh-rate true
-}
-
-// Generic fullscreen request (any app asking to go fullscreen)
-window-rule {
-    match is-focused=true
-    variable-refresh-rate true
 }
 
 // Wine System Tray: hide the empty host window off-screen