feat(puppet): add bone_world_scale public API

Returns cascaded world.scl_x and scl_y for a bone. Used by puppet-test
Group 8 scale-cascade assertions; future: vagrant-skeleton or other
modules can query world-scale for compositing/effects.

init.lua

@@ -468,6 +468,22 @@ function M.bone_world_transform(handle, bone_id)
     return ws.x, ws.y, ws.rot
 end
 
+-- ====================================================================
+-- World-scale query (public API; reads from cached bone_state.world).
+-- Returns scl_x, scl_y of the bone's cached world-state.
+-- ====================================================================
+function M.bone_world_scale(handle, bone_id)
+    local p = all_puppets[handle]
+    if p == nil then
+        error("puppet.bone_world_scale: handle " .. tostring(handle) .. " not spawned")
+    end
+    local ws = p.bone_state[bone_id] and p.bone_state[bone_id].world
+    if ws == nil then
+        error("puppet.bone_world_scale: bone '" .. tostring(bone_id) .. "' has no cached world-state")
+    end
+    return ws.scl_x, ws.scl_y
+end
+
 -- ====================================================================
 -- Test-only: direct bone-angle write bypassing track-conflict guard.
 -- Stored in test_overrides and applied during update after rest-reset