refactor(render3d): programs, GPU timers and the context behind gpu.ludic

The last of milestone 1: no OpenGL call is left in render3d outside gpu.ludic but the clock
and the CPU-side buffer helpers.

- gpu_program builds a program and remembers the variant it came from (vertex, fragment and
  defines as one line - the SPIR-V manifest's key), so a backend that cannot compile at run
  time finds the pipeline for the same handle. gpu_use_program and gpu_program_free replace
  32 uses and 2 frees; the overlay's program is recorded under overlay.vert|overlay.frag.
- gpu_query_new / _begin / _end / _result carry R3D_PROF's timers.
- gpu_open, gpu_vsync, gpu_renderer_name and gpu_resize_check carry the context.
- r3d_program_tess is gone: nothing called it and no tessellation shader exists.
- R3D_GLCHECK also checks after framebuffer and renderbuffer changes, viewport, draw buffers,
  program use, texture parameters, the resize check and between frames.

OpenGL frames are byte-identical at the five viewpoints; 59 self-tests pass with and without
R3D_GLCHECK, with no GL error; ludic-dev test 140 passed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/ludic.render3d/water.ludic

@@ -137,7 +137,7 @@ function water_init(level: int, cx: int, cz: int, ex: int, ez: int) -> void {
 function water_draw(depth_tex: int) -> void {
   if not water_on or wb_n == 0 { return }
   let p = water_prog
-  gl_use_program(p)
+  gpu_use_program(p)
   u_mat4(gpu_uniform(p, "u_view"), cam_view)
   u_mat4(gpu_uniform(p, "u_proj"), cam_proj)
   u_mat4(gpu_uniform(p, "u_inv_vp"), cam_inv_vp)