bump: minor
type: feat
Entity-pool stats (#80). Ludic's ECS is already pool-based: the allocator recycles freed entity slots through a freelist (a `despawn`ed slot is reused by the next `spawn` before any new slot is taken), and component storage is fixed per-entity arrays — so spawning and despawning many entities per frame (bullet-hell / horde) does **no per-spawn heap allocation** and cannot fragment. Exposes that with a `Pool.*` namespace so a game can watch the reuse and budget against the cap: `Pool.live()` (entities alive now), `Pool.free()` (freed slots waiting to be reused), `Pool.reserved()` (high-water — slots ever allocated; stays flat across a steady spawn/despawn loop, the proof that slots are pooled not reallocated), and `Pool.capacity()` (the fixed entity cap). Zero-cost — they read the existing allocator counters inline. Example: `examples/library/pool.ludic`.