post-TUI lag: autosuggestion culprit confirmed; add self-heal hook

A/B in a live lagging shell: disabling fish_autosuggestion_enabled cures
the lag instantly, and re-enabling does NOT bring it back — the toggle
resets the wedged reader state. __autosuggestion_unwedge (fish_postexec)
now applies that reset after every command, at the moment TUIs exit.
Builtins only, invisible, respects a deliberate manual disable. Flight
recorder stays armed until the hook is proven in real use.

Also from this investigation: wedged-thread evidence (sampler attach
cures), lag-sample tool, flight recorder in the zellij fish wrapper.

platforms/home-manager/modules/nmasur/presets/programs/lag-triage/default.nix

@@ -32,6 +32,15 @@ in
         description = "Reset terminal state left behind by a TUI";
         body = builtins.readFile ./unlag.fish;
       };
+      lag-sample = {
+        description = "Stack-sample fish and zellij while typing lag is happening";
+        body = builtins.readFile ./lag-sample.fish;
+      };
+      __autosuggestion_unwedge = {
+        description = "Reset autosuggestion state after each command to prevent post-TUI typing lag";
+        onEvent = "fish_postexec";
+        body = builtins.readFile ./autosuggestion-unwedge.fish;
+      };
     };
 
   };