fix(web): force WebGL2 backend

Affected Chromium adapters fail after selecting WebGPU even when packed renderer paths are forced. Use WebGL2 for the web app and let device limits select renderer tiers.\n\nRefs #788

src/app/mod.rs

@@ -3723,6 +3723,7 @@ pub fn run_web() -> iced::Result {
     .subscription(OpenCADStudio::subscription)
     .title(|_state: &OpenCADStudio| "Open CAD Studio".to_string())
     .theme(|state: &OpenCADStudio| state.active_theme.clone())
+    .backend(iced::Backend::Hardware(iced::backend::Api::OpenGL))
     .font(iced_aw::ICED_AW_FONT_BYTES)
     .run()
 }

src/scene/pipeline/device_capabilities.rs

@@ -1,8 +1,6 @@
 use iced::wgpu;
 
 /// Renderer-relevant limits of the selected GPU device.
-///
-/// Native devices select by limits; browser builds use compatibility paths.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct DeviceCapabilities {
     pub max_storage_buffers_per_shader_stage: u32,

src/scene/pipeline/mod.rs

@@ -560,12 +560,12 @@ impl Pipeline {
         );
 
         // ── Wire pipeline ──────────────────────────────────────────────────
-        // Browser shader support can lag behind advertised WebGPU limits.
+        // Select the renderer tier from device limits.
         let device_caps = DeviceCapabilities::detect(device);
         #[cfg(not(target_arch = "wasm32"))]
         let force_compat_renderer = crate::cli::gui_config().compat_renderer;
         #[cfg(target_arch = "wasm32")]
-        let force_compat_renderer = true;
+        let force_compat_renderer = false;
         let wire_mode =
             wire_gpu::WirePipelineMode::select(device_caps, force_compat_renderer);
         let wire_const_bgl = wire_mode