feat: Enable dynamic shovel pricing calculation (#15)

src/features/grid/components.rs

@@ -74,4 +74,19 @@ impl Grid {
         *tile_state = mapper(&*tile_state);
         Ok(())
     }
-}
+
+    pub fn count_claimed_tiles(&self, tile_query: &Query<&TileState>) -> u32 {
+        self.tiles
+            .iter()
+            .flatten()
+            .filter(|&entity| {
+                if let Ok(state) = tile_query.get(*entity) {
+                    !matches!(state, TileState::Unclaimed)
+                } else {
+                    false
+                }
+            })
+            .count() as u32
+    }
+}
+