fix(hud): improved kill tracking with Shrapnel heuristic

- Non-Shrapnel loot = definite kill
- Shrapnel: every 2 Shrapnel = 1 kill (since mobs drop 1-2 Shrapnel)
- This handles mobs that drop only Shrapnel
- Reset Shrapnel counter on session start

ui/main_window.py

@@ -890,6 +890,9 @@ class MainWindow(QMainWindow):
         self.set_session_state(SessionState.RUNNING)
         self.current_session_id = project_id
         
+        # Reset shrapnel counter for kill tracking
+        self._shrapnel_count = 0
+        
         # Emit signal
         self.session_started.emit(project_id)
         
@@ -958,10 +961,21 @@ class MainWindow(QMainWindow):
             if item_name == 'Universal Ammo':
                 return
             
-            # Count kills (excluding Shrapnel which is from every mob)
-            # Real loot items indicate a kill
+            # Kill tracking heuristic:
+            # - Non-Shrapnel loot = definite kill
+            # - Shrapnel: count as kill every 2 Shrapnel (since mobs drop 1-2 Shrapnel)
             if item_name != 'Shrapnel':
                 self.hud.update_stats({'kills_add': 1})
+            else:
+                # Track Shrapnel count for this session
+                if not hasattr(self, '_shrapnel_count'):
+                    self._shrapnel_count = 0
+                self._shrapnel_count += quantity
+                # Every 2 Shrapnel = 1 kill (approximate)
+                kills_from_shrapnel = self._shrapnel_count // 2
+                if kills_from_shrapnel > 0:
+                    self.hud.update_stats({'kills_add': kills_from_shrapnel})
+                    self._shrapnel_count -= kills_from_shrapnel * 2
             
             # Queue database write for main thread (SQLite thread safety)
             if self._current_db_session_id: