feat(input,ecs): #79 Input.axis_i directional int + #84 world bounds

#79 — Input.axis_i(neg,pos) -> int returns a -1/0/1 movement intent from the
multi-key device set, so WASD-to-movement needs no bool->int glue and feeds an
int mover directly (dx = Input.axis_i('a','d')).

#84 — a Bounds config entity (rect + policy, from ludic.core) drives the
engine-owned world-bounds system (LateUpdate): clamp / wrap / bounce (clamp +
flip Body velocity) / kill (despawn a body fully outside). Reads the Collider
size so the box stays inside; off by default, spliced only when Bounds is
declared (byte-identical otherwise). Adds World.despawn(e) — the by-id
reflective despawn (runs @OnDespawn + frees) via a new world_despawn intrinsic
whose @fn_world_despawn helper is emitted in emit_program's tail once a use is
seen (the g_uses_* prelude pattern), used by the kill policy and callable from
any system.

Examples input_movement + world_bounds. Full suite 112/0, goldens
byte-identical, fixpoint holds.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/ludic.core/package.ludic

@@ -21,3 +21,4 @@ provides "Body"
 provides "Collider"
 provides "Solids"
 provides "Sprite"
+provides "Bounds"