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/actor.ludic

@@ -33,7 +33,7 @@ property Actor {
   row:     int = -1,       # where it stands in ac_actors, so it leaves in O(1); -1 off the stage
   cutout:  bool = false,   # alpha-tested (a flame's cards)
   emissive: float = 0.0,       # float bits: self-lit strength
-  skin:    Skin,           # this instance's own pose (skin_clone); null: the model's
+  @owns(SkinClone) skin:    Skin,           # this instance's own pose (skin_clone); null: the model's
   skin_owned: bool = false, # made by actor_own_skin: actor_release frees it
   ptint:   words,          # 4 per primitive: on flag, r, g, b (a part's own colour)
   hide:    words,          # 1 per primitive: skip it (a cap taken off)

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,

packages/ludic.render3d/gpu_vk_res.ludic

@@ -634,6 +634,7 @@ function gvk_sampler(render3d_st: mut Render3dState, min_f: int, mag_f: int, wra
 # destroyed at gvk_retire_flush, after the frame's work is done.
 
 @alloc_ok("loading a model, a texture or a font: a load, not a frame (a guest loading a teammate's look is one)")
+@creates(GpuBuffer)
 function gvk_buf_new(render3d_st: mut Render3dState) -> int {
   let zero: long = 0
   if render3d_st.gvk_buf == null {
@@ -655,6 +656,7 @@ function gvk_buf_new(render3d_st: mut Render3dState) -> int {
 
 # a buffer done with for good (a mesh freed): its storage goes, and its handle is handed out again
 # by gvk_buf_new. gvk_buf_release alone keeps the handle, for a caller that fills it again.
+@releases(GpuBuffer)
 function gvk_buf_delete(render3d_st: mut Render3dState, b: int) -> void {
   if b <= 0 or b >= len(render3d_st.gvk_buf) { return }
   gvk_buf_release(render3d_st, b)

packages/ludic.render3d/mesh.ludic

@@ -7,7 +7,7 @@
 property Mesh {
   vao:   int = 0,            # OpenGL's vertex array object (gpu.ludic's, on that backend)
   vbo:   int = 0,            # the first vertex buffer
-  ebo:   int = 0,
+  @owns(GpuBuffer) ebo:   int = 0,
   count: int = 0,            # indices (ebo != 0) or vertices
   mode:  int = 4,            # GL_TRIANGLES
   itype: int = 0x1405,       # GL_UNSIGNED_INT

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
 }