refactor(engine): audit and rationalize platform cfg gates (closes #49)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

solitaire_engine/src/ui_modal.rs

@@ -55,6 +55,7 @@ use bevy::window::PrimaryWindow;
 use solitaire_data::AnimSpeed;
 
 use crate::font_plugin::FontResource;
+use crate::platform::SHOW_KEYBOARD_ACCELERATORS;
 use crate::settings_plugin::SettingsResource;
 use crate::ui_theme::{
     scaled_duration, ACCENT_PRIMARY, ACCENT_PRIMARY_HOVER, ACCENT_SECONDARY, BG_BASE, BG_ELEVATED,
@@ -342,7 +343,7 @@ pub fn spawn_modal_button<M: Component>(
     variant: ButtonVariant,
     font_res: Option<&FontResource>,
 ) {
-    let hotkey = if cfg!(target_os = "android") { None } else { hotkey };
+    let hotkey = if SHOW_KEYBOARD_ACCELERATORS { hotkey } else { None };
     let font_handle = font_res.map(|f| f.0.clone()).unwrap_or_default();
     let font_label = TextFont {
         font: font_handle.clone(),