fix: add benchmark recording to calculate_provisional_path

Provisional paths were not being recorded to benchmark stats, causing
total_paths=0 while failed_paths accumulated. Now records:
- path_calc_times_us (timing)
- path_lengths (path length)
- nodes_expanded (A* nodes visited)
- failed_paths (when start/goal not standable)

pathfinding_benchmark_current.csv

@@ -1,4 +1,4 @@
 sample,path_duration_us,path_length,nodes_expanded,success
 # Summary
 # total_paths,0
-# failed_paths,0
+# failed_paths,1906

src/entities/shared_systems/pathfinding.rs

@@ -579,13 +579,24 @@ pub fn calculate_provisional_path(
     goal: IVec3,
     node_limit: usize,
 ) -> Vec<Vec3> {
+    let timer = Instant::now();
+
     if !is_standable_tile(tilemap, start) {
+        LOCAL_FAILED_PATHS.with(|f| {
+            *f.borrow_mut() += 1;
+        });
+        return Vec::new();
+    }
+    if !is_standable_tile(tilemap, goal) {
+        LOCAL_FAILED_PATHS.with(|f| {
+            *f.borrow_mut() += 1;
+        });
         return Vec::new();
     }
 
     let estimated_tiles = octile_distance_3d(start, goal) / ITILE_SIZE;
 
-    SCRATCHPAD.with(|s| {
+    let result = SCRATCHPAD.with(|s| {
         let mut scratch = s.borrow_mut();
         let capacity = ((estimated_tiles as usize).max(64)).min(4096);
         scratch.clear_and_reserve(capacity);
@@ -613,11 +624,17 @@ pub fn calculate_provisional_path(
             }
 
             if current == goal {
-                return reconstruct_path(&scratch.came_from, current);
+                return (
+                    reconstruct_path(&scratch.came_from, current),
+                    nodes_expanded,
+                );
             }
 
             if nodes_expanded >= node_limit {
-                return reconstruct_path(&scratch.came_from, best_node);
+                return (
+                    reconstruct_path(&scratch.came_from, best_node),
+                    nodes_expanded,
+                );
             }
 
             scratch.closed_set.insert(current);
@@ -651,8 +668,24 @@ pub fn calculate_provisional_path(
             }
         }
 
-        reconstruct_path(&scratch.came_from, best_node)
-    })
+        (
+            reconstruct_path(&scratch.came_from, best_node),
+            nodes_expanded,
+        )
+    });
+
+    let elapsed = timer.elapsed().as_micros();
+    LOCAL_PATH_TIMES.with(|t| {
+        t.borrow_mut().push(elapsed);
+    });
+    LOCAL_PATH_LENGTHS.with(|l| {
+        l.borrow_mut().push(result.0.len());
+    });
+    LOCAL_NODES_EXPANDED.with(|n| {
+        n.borrow_mut().push(result.1);
+    });
+
+    result.0
 }
 
 pub fn bench_report_system(