Rename the fast preview to the shaded preview

Its shader files, the name they are registered under, its members and
the panel text now match what it does: shading only, no geometry.

resources/shaders/110/texture_displacement_shaded.fs

@@ -1,6 +1,6 @@
 #version 110
 
-// See resources/shaders/140/texture_displacement_bump.fs for full documentation; this is the
+// See resources/shaders/140/texture_displacement_shaded.fs for full documentation; this is the
 // GLSL 1.10 compatibility variant (same logic, older syntax).
 
 #define INTENSITY_CORRECTION 0.6
@@ -309,7 +309,7 @@ void main()
     bool have_uv     = false;
 
     if (use_vertex_uv) {
-        // Mikkelsen surface-gradient bump; see the 140 variant for the full rationale. Scale-exact
+        // Mikkelsen surface-gradient normal perturbation; see the 140 variant for the full rationale. Scale-exact
         // for a conformal LSCM map (no global 1/tiling assumption), and gated by the paint weight
         // via a multiply so the branch stays uniform (use_vertex_uv is a uniform).
         vec2 uv = (island_active > 0.5)

resources/shaders/110/texture_displacement_shaded.vs

@@ -1,6 +1,6 @@
 #version 110
 
-// See resources/shaders/140/texture_displacement_bump.vs for full documentation; this is the
+// See resources/shaders/140/texture_displacement_shaded.vs for full documentation; this is the
 // GLSL 1.10 compatibility variant.
 
 uniform mat4 view_model_matrix;

resources/shaders/110/texture_displacement_uvcheck.fs

@@ -22,7 +22,7 @@ uniform vec2  uv_offset;
 uniform bool  use_vertex_uv;
 // The in-shader projection (0 Triplanar, 1 Cylindrical, 2 Spherical) and the painted patch's frame the
 // wrapping ones wrap around, in the texture frame - the same uniforms, and the same formulas, as
-// texture_displacement_bump.fs, so the checker reports the projection the bake will actually use.
+// texture_displacement_shaded.fs, so the checker reports the projection the bake will actually use.
 uniform int   projection_mode;
 uniform vec3  patch_center;
 uniform vec3  patch_axis;
@@ -91,7 +91,7 @@ void main()
     if (any(lessThan(clipping_planes_dots, ZERO)))
         discard;
 
-    // World space anchored at the volume's origin, like the bake and the bump preview.
+    // World space anchored at the volume's origin, like the bake and the shaded preview.
     vec3 triangle_normal = normalize(cross(dFdx(world_pos.xyz), dFdy(world_pos.xyz)));
     vec3 tex_pos = world_pos.xyz - tex_anchor;
     if (volume_mirrored)