render3d: 671 frame-reachable allocation sites to 161 - declared, split, or made nothing

@alloc_ok with its reason on what is made once per resource and kept (textures, programs, samplers,
views, layouts, memory blocks, the pipeline cache in gvk_pipe_build), on resize and swapchain
remakes, on screenshots and dumps, on a world being set up (streams, layers, water, post, bakes), on
loads (gltf_load, skin_load, tex_load*, png_decode, fonts) and on R3D_PROF / drawstats.
gltf_cached's hit path is its own and makes nothing; the miss (gltf_cached_load) is declared.
m4_look_at (now over m4_look_at_xyz) and m4_inverse work on scalars, and cam_update makes no scratch.
Left: lazy first-use starts, error and debug prints, and scratch made and freed each call (churn,
plan 25.3). Compiled (steady, and ludic deps over the game).

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

packages/ludic.render3d/gpu.ludic

@@ -357,6 +357,7 @@ function gpu_gl_usage(u: int) -> int {
 }
 
 # a new mesh, its vertex array bound: the vertex, attribute and index calls below describe it
+@alloc_ok("loading a model, a texture or a font: a load, not a frame (a guest loading a teammate's look is one)")
 function gpu_mesh_new(render3d_st: Render3dState) -> Mesh {
   let m = new Mesh
   m.attrs = words(GPU_MAX_ATTRS * GPU_ATTR_W)