feat(render3d): texture filtering and shadow resolution a game can change while it runs

- r3d_set_anisotropy(level) updates every mipmapped texture already loaded (OpenGL parameter,
  Vulkan sampler record), not only later uploads; the game's setting never reached the scanned
  materials, which load before the settings are read.
- shadow_set_res(size) remakes the cascades at 1024 / 2048 / 4096 (shadow_res replaces the
  SHADOW_RES constant); lighting.glsl reads the texel size from the map, so OpenGL frames at
  2048 are unchanged.

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

packages/ludic.render3d/shaders/lighting.glsl

@@ -109,7 +109,7 @@ float shadowSample(int c, vec3 wpos, float biasWorld) {
   vec3 p = lp.xyz / lp.w * 0.5 + 0.5;
   if (p.x < 0.0 || p.x > 1.0 || p.y < 0.0 || p.y > 1.0 || p.z > 1.0) return 1.0;
   float bias = biasWorld / cascadeRange(c);
-  float texel = 1.0 / 2048.0;
+  float texel = 1.0 / float(textureSize(u_shadow, 0).x);   // the shadow resolution setting
   float r = ign(gl_FragCoord.xy) * 6.2831853;
   float cs = cos(r), sn = sin(r);
   mat2 rot = mat2(cs, sn, -sn, cs);