Command markers only with the debug setting; removing a marker clears them at once

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/game.rs

@@ -4316,7 +4316,9 @@ impl Game {
     }
 
     pub fn add_mark(&mut self, x: f32, y: f32, kind: u8, side: u8, duration: f32, fixed: bool) {
-        if (!fixed && !self.debug_markers) || duration <= 0.0 || !x.is_finite() || !y.is_finite() {
+        // the shields, swords and the flag show themselves; these markers are for debugging only
+        let _ = fixed;
+        if !self.debug_markers || duration <= 0.0 || !x.is_finite() || !y.is_finite() {
             return;
         }
         let until = self.sim_steps + (duration / STEP).ceil() as u64;