fix(render): transparency toggle also governs hatches, text and fills

Only the wire shaders read transparency_enable; hatch (solid, gradient
and pattern), text and 3D/fill-triangle fragments always drew the
entity's alpha, so turning Show Transparency off left them see-through.

Fixes #1529

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

src/shaders/block_text.wgsl

@@ -72,5 +72,5 @@ fn fs_main(in: VertOut) -> @location(0) vec4<f32> {
     if alpha <= 0.0 {
         discard;
     }
-    return vec4<f32>(in.color.rgb, in.color.a * alpha);
+    return vec4<f32>(in.color.rgb, select(1.0, in.color.a, u.transparency_enable > 0.5) * alpha);
 }