perf(city): optimize rendering for expanded city bounds

Tighten directional light shadow frustum to follow the player and
batch static geometries into merged meshes, reducing draw calls
significantly. Expand city world bounds to support 72 blocks and
add per-frame performance monitoring instrumentation.

BREAKING CHANGE: city bounds changed from ±80 to ±120/±160, update
any hardcoded client-side world assumptions.

database/seeders/CityWorldSeeder.php

@@ -28,10 +28,13 @@ class CityWorldSeeder extends Seeder
             ['slug' => 'city10'],
             [
                 'name' => 'City10',
-                'bounds_min_x' => -80,
-                'bounds_max_x' => 80,
-                'bounds_min_z' => -80,
-                'bounds_max_z' => 80,
+                // Performance-tuned size: 72 blocks (9 × 8) after the
+                // 40-unit road grid and its outer margin are derived from
+                // these bounds (layout −160..200 × −160..160).
+                'bounds_min_x' => -120,
+                'bounds_max_x' => 160,
+                'bounds_min_z' => -120,
+                'bounds_max_z' => 120,
                 'is_active' => true,
                 'expansions' => 0,
             ],