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/programs.ludic

@@ -64,9 +64,9 @@ function r3d_bind_2d(render3d_st: mut Render3dState, prog: int, name: string, un
 
 # A framebuffer with one colour texture (and optionally a depth texture).
 property Target {
-  fbo:   int = 0,
-  color: int = 0,
-  depth: int = 0,
+  @owns(GpuFramebuffer) fbo:   int = 0,
+  @owns(GpuTexture) color: int = 0,
+  @owns(GpuTexture) depth: int = 0,
   w:     int = 0,
   h:     int = 0
 }