chore: silence native and wasm build warnings

Gate target-specific code so neither build warns about the other's items:
native-only helpers (view, window icon, file dialogs, file association, plugin
host/guard/registry, self-update) are cfg'd to non-wasm; the wasm-only font
fallback (script_of / cjk_lang / request) is cfg'd to wasm. Drop an unused mut,
allow the few genuinely-conditional dead items (mesh_click_hit, GPU layout
helpers, parity stubs), and gate the embedded PlotSettings-unrelated dead
constants. Both targets now build clean (only the unavoidable nom/quick-xml
future-incompat dependency notice remains).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/app/document.rs

@@ -159,6 +159,7 @@ pub(super) struct DocumentTab {
     /// rest of the code can treat it as a normal tab when reading.
     pub(super) is_start: bool,
     /// Per-plugin document state (`plugin::BuiltinPlugin` manifest id → state).
+    #[cfg_attr(target_arch = "wasm32", allow(dead_code))]
     pub(super) plugin_state: HashMap<&'static str, Box<dyn Any + Send + Sync>>,
     pub(super) suspended_cmd: Option<Box<dyn CadCommand>>,
 }

src/app/helpers.rs

@@ -286,6 +286,7 @@ pub(super) fn title_case_word(value: &str) -> String {
 // ── Window icon ────────────────────────────────────────────────────────────
 
 /// Builds a 32×32 RGBA icon: red background with OCS drawn in white pixels.
+#[cfg(not(target_arch = "wasm32"))]
 pub(super) fn build_window_icon() -> Vec<u8> {
     const W: usize = 32;
     const SZ: usize = W * W * 4;

src/app/mod.rs

@@ -11,6 +11,7 @@ mod history;
 mod layers;
 mod model_ops;
 mod mtext_editor;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod plugin_host;
 mod properties;
 mod settings;
@@ -819,6 +820,7 @@ pub enum ModalKind {
     DimStyle,
     Unsaved,
     SaveDialog,
+    #[cfg_attr(target_arch = "wasm32", allow(dead_code))]
     AssocPrompt,
     PointStyle,
 }
@@ -2020,6 +2022,7 @@ impl OpenCADStudio {
     /// open. Secondary manager windows are unavailable on the web for now.
     #[cfg(target_arch = "wasm32")]
     fn boot_web() -> (Self, Task<Message>) {
+        #[cfg_attr(target_arch = "wasm32", allow(unused_mut))]
         let mut s = Self::new();
         let focus = s.focus_cmd_input();
         (s, focus)

src/app/update.rs

@@ -238,6 +238,7 @@ impl OpenCADStudio {
 
     /// Snapshot of disabled plugin ids — lets the registry skip them while it
     /// holds a `&mut` borrow of the app via `HostSession`.
+    #[cfg(not(target_arch = "wasm32"))]
     pub(crate) fn disabled_plugin_ids(&self) -> rustc_hash::FxHashSet<String> {
         self.disabled_plugins.clone()
     }

src/app/view.rs

@@ -38,6 +38,7 @@ impl std::fmt::Display for RenderModeChoice {
 }
 
 impl OpenCADStudio {
+    #[cfg(not(target_arch = "wasm32"))]
     pub fn view(&self, window_id: window::Id) -> Element<'_, Message> {
         // ── Floating panel windows ─────────────────────────────────────────
         // All dialogs are in-canvas modals now (Plan B); view_main stacks the
@@ -3893,6 +3894,7 @@ pub(super) fn start_page_view<'a>() -> Element<'a, Message> {
     .spacing(12)
     .align_y(iced::Center);
 
+    #[cfg_attr(target_arch = "wasm32", allow(unused_mut))]
     let mut secondary_row = row![
         outline_btn(
             "Send Feedback",