render3d: @owns on the handles records hold

Target's framebuffer and its colour and depth textures, a Mesh's index buffer (gvk_buf_new /
gvk_buf_delete now @creates / @releases GpuBuffer too), a Prim's mesh and an Actor's own skin clone.
ludic deps --resources over main: resource_drops 0, owned_leaks 0; a probe freeing a Target's fbo
alone was reported for its colour and depth (2), then removed. Compiled (steady).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.render3d/gltf.ludic

@@ -6,7 +6,7 @@
 # ============================================================================
 
 property Prim {
-  mesh: Mesh,
+  @owns(Mesh) mesh: Mesh,
   diff: int = 0,
   nrm:  int = 0,
   arm:  int = 0,