Move resource limits to a dedicated struct, restore before preexec

src/Command.zig

@@ -176,13 +176,13 @@ fn startPosix(self: *Command, arena: Allocator) !void {
         // We don't log because that'll show up in the output.
     };
 
+    // Restore any rlimits that were set by Ghostty. This might fail but
+    // any failures are ignored (its best effort).
+    global_state.rlimits.restore();
+
     // If the user requested a pre exec callback, call it now.
     if (self.pre_exec) |f| f(self);
 
-    if (global_state.rlimits.nofile) |lim| {
-        internal_os.restoreMaxFiles(lim);
-    }
-
     // Finally, replace our process.
     _ = posix.execveZ(pathZ, argsZ, envp) catch null;