feat(web): unify fonts and refine viewcube

Preload one language-aware font resource across the interface, drawing text, and navigation labels.\n\nRender the navigation cube, ring, outlines, and labels through a 4x MSAA target.

src/shaders/viewcube.wgsl

@@ -1,4 +1,4 @@
-// ViewCube shader — Phong lighting + hover highlight.
+// ViewCube shader — flat surface fill, hover highlight, and edge lines.
 
 struct Uniforms {
     view_proj:    mat4x4<f32>,
@@ -26,9 +26,22 @@ fn fs_main(in: VOut) -> @location(0) vec4<f32> {
     let is_hovered = abs(in.region_f - u.hover_region.x) < 0.001 && u.hover_region.x >= 0.0;
     var final_rgb = in.color;
     if is_hovered {
-        let glow = vec3<f32>(0.68, 0.88, 1.0);
-        final_rgb = mix(final_rgb, glow, 0.60);
-        final_rgb = clamp(final_rgb * 1.30, vec3<f32>(0.0), vec3<f32>(1.0));
+        final_rgb = vec3<f32>(0.20, 0.72, 0.66);
     }
     return vec4<f32>(final_rgb, 1.0);
 }
+
+struct LineIn {
+    @location(0) pos: vec3<f32>,
+}
+
+@vertex
+fn line_vs_main(in: LineIn) -> @builtin(position) vec4<f32> {
+    let rotated = (u.rotation * vec4<f32>(in.pos, 1.0)).xyz;
+    return u.view_proj * vec4<f32>(rotated, 1.0);
+}
+
+@fragment
+fn line_fs_main() -> @location(0) vec4<f32> {
+    return vec4<f32>(0.05, 0.08, 0.13, 1.0);
+}

src/shaders/viewcube_composite.wgsl

@@ -0,0 +1,44 @@
+struct VertexOutput {
+    @builtin(position) position: vec4<f32>,
+    @location(0) uv: vec2<f32>,
+}
+
+struct CompositeUniforms {
+    uv_scale: vec2<f32>,
+    _pad: vec2<f32>,
+}
+
+var<private> POSITIONS: array<vec2<f32>, 6> = array<vec2<f32>, 6>(
+    vec2<f32>(-1.0,  1.0),
+    vec2<f32>(-1.0, -1.0),
+    vec2<f32>( 1.0,  1.0),
+    vec2<f32>(-1.0, -1.0),
+    vec2<f32>( 1.0, -1.0),
+    vec2<f32>( 1.0,  1.0),
+);
+
+var<private> UVS: array<vec2<f32>, 6> = array<vec2<f32>, 6>(
+    vec2<f32>(0.0, 0.0),
+    vec2<f32>(0.0, 1.0),
+    vec2<f32>(1.0, 0.0),
+    vec2<f32>(0.0, 1.0),
+    vec2<f32>(1.0, 1.0),
+    vec2<f32>(1.0, 0.0),
+);
+
+@vertex
+fn vs_main(@builtin(vertex_index) index: u32) -> VertexOutput {
+    var output: VertexOutput;
+    output.position = vec4<f32>(POSITIONS[index], 0.0, 1.0);
+    output.uv = UVS[index];
+    return output;
+}
+
+@group(0) @binding(0) var resolved_texture: texture_2d<f32>;
+@group(0) @binding(1) var resolved_sampler: sampler;
+@group(0) @binding(2) var<uniform> uniforms: CompositeUniforms;
+
+@fragment
+fn fs_main(input: VertexOutput) -> @location(0) vec4<f32> {
+    return textureSample(resolved_texture, resolved_sampler, input.uv * uniforms.uv_scale);
+}

src/shaders/viewcube_text.wgsl

@@ -8,7 +8,7 @@ struct Uniforms {
 @group(0) @binding(2) var tex: texture_2d<f32>;
 
 struct VsIn {
-    @location(0) pos: vec2<f32>,
+    @location(0) pos: vec3<f32>,
     @location(1) uv: vec2<f32>,
     @location(2) color: vec4<f32>,
 };
@@ -26,7 +26,7 @@ fn vs_main(input: VsIn) -> VsOut {
         (input.pos.x / u.screen.x) * 2.0 - 1.0,
         1.0 - (input.pos.y / u.screen.y) * 2.0
     );
-    out.pos = vec4<f32>(ndc, 0.0, 1.0);
+    out.pos = vec4<f32>(ndc, input.pos.z, 1.0);
     out.uv = input.uv;
     out.color = input.color;
     return out;