cuda.core: scope texture/surface PR to the core API + fluid examples (#2188 decision 7)

Per #2188 decision 7, the texture/surface example showcase is orthogonal to the
core API and lands in a follow-up. Move the 15 standalone gl_interop_*.py demos
(bloom, caustics, clouds, fire, image_show, jfa_voronoi, lenia, mandelbrot,
mipmap_lod, ocean, particles, physarum, reaction_diffusion, sdf_volume,
texture_filter) onto the feature/cuda-core-texture-examples-467 branch for
continued iteration and a future examples PR.

Kept here as the representative end-to-end coverage of the new API:
- examples/texture_sample.py (canonical sampling smoke test),
- examples/gl_interop_fluid.py (cuda.core CUDAArray/TextureObject/SurfaceObject),
- examples/gl_interop_fluid_numba_cuda_mlir.py (numba-cuda-mlir port) + its
  isolated pixi env.

Drop the moved examples from the example-test requirements map; gl_interop_fluid
and the pre-existing gl_interop_plasma stay wired.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: rparolin