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

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

solitaire_engine/src/card_plugin.rs

@@ -14,9 +14,8 @@ use std::collections::{HashMap, HashSet};
 
 use bevy::color::Color;
 use bevy::prelude::*;
-use bevy::window::WindowResized;
-#[cfg(target_os = "android")]
 use bevy::sprite::Anchor;
+use bevy::window::WindowResized;
 use solitaire_core::card::{Card, Rank, Suit};
 use solitaire_core::game_state::{DrawMode, GameState};
 use solitaire_core::pile::PileType;
@@ -26,13 +25,14 @@ use solitaire_core::rules::{can_place_on_foundation, can_place_on_tableau};
 use crate::animation_plugin::{CardAnim, EffectiveSlideDuration, CARD_ANIM_Z_LIFT};
 use crate::card_animation::CardAnimation;
 use crate::events::{CardFaceRevealedEvent, CardFlippedEvent, StateChangedEvent};
+use crate::font_plugin::FontResource;
 use crate::game_plugin::GameMutation;
 use crate::layout::{Layout, LayoutResource, LayoutSystem};
 use crate::pause_plugin::PausedResource;
+use crate::platform::USE_TOUCH_UI_LAYOUT;
 use crate::resources::{DragState, GameStateResource};
 use crate::settings_plugin::{SettingsChangedEvent, SettingsResource};
 use crate::table_plugin::{PileMarker, PILE_MARKER_DEFAULT_COLOUR};
-use crate::font_plugin::FontResource;
 use crate::ui_theme::{
     CARD_SHADOW_ALPHA_DRAG, CARD_SHADOW_ALPHA_IDLE, CARD_SHADOW_COLOR, CARD_SHADOW_LOCAL_Z,
     CARD_SHADOW_OFFSET_DRAG, CARD_SHADOW_OFFSET_IDLE, CARD_SHADOW_PADDING_DRAG,
@@ -73,10 +73,9 @@ pub const STACK_FAN_FRAC: f32 = 0.025;
 /// Font size as a fraction of card width.
 const FONT_SIZE_FRAC: f32 = 0.28;
 
-/// Font-size fraction for the large-print readability overlay on Android.
+/// Font-size fraction for the large-print readability overlay on touch HUD layouts.
 /// Spawned on top of PNG face cards to make the rank+suit legible at phone
 /// scale, where the baked-in PNG corner text is only ~10 px physical.
-#[cfg(target_os = "android")]
 const FONT_SIZE_FRAC_MOBILE: f32 = 0.35;
 
 /// Card-face background — Terminal `#1a1a1a` (BG_ELEVATED).
@@ -177,13 +176,12 @@ pub struct CardEntity {
 #[derive(Component, Debug)]
 pub struct CardLabel;
 
-/// Marker for the large-print rank+suit corner overlay on Android.
+/// Marker for the large-print rank+suit corner overlay used by touch HUD layouts.
 ///
 /// Spawned on top of PNG face cards (face-up only) at font size
 /// [`FONT_SIZE_FRAC_MOBILE`] so the rank and suit character are
 /// readable at phone scale. Only exists when `CardImageSet` is present
 /// (the fallback solid-colour path uses a plain `CardLabel` instead).
-#[cfg(target_os = "android")]
 #[derive(Component, Debug, Clone)]
 struct AndroidCornerLabel(pub String);
 
@@ -192,10 +190,11 @@ struct AndroidCornerLabel(pub String);
 /// Covers the card art's own small corner rank/suit text so only the
 /// large overlay is visible. Sized at [`FONT_SIZE_FRAC_MOBILE`]-derived
 /// dimensions and coloured [`CARD_FACE_COLOUR`] to match the card face.
-#[cfg(target_os = "android")]
 #[derive(Component, Debug, Clone, Copy)]
 struct AndroidCornerBg;
 
+type AndroidCornerBgFilter = (With<AndroidCornerBg>, Without<AndroidCornerLabel>);
+
 /// Marker component indicating the card is currently highlighted as a hint.
 /// `remaining` counts down in real seconds; the highlight is removed when it
 /// reaches zero and the card sprite colour is restored to its normal value.
@@ -465,7 +464,6 @@ impl Plugin for CardPlugin {
                 ),
             );
 
-        #[cfg(target_os = "android")]
         app.add_systems(Update, resize_android_corner_labels);
     }
 }
@@ -920,15 +918,11 @@ fn spawn_card_entity(
             ));
         });
     }
-    #[cfg(target_os = "android")]
-    if card_images.is_some() {
+    if USE_TOUCH_UI_LAYOUT && card_images.is_some() {
         entity.with_children(|b| {
             add_android_corner_label(b, card, layout.card_size, color_blind, high_contrast, font_handle);
         });
     }
-    // Suppress unused-variable warning when not building for Android.
-    #[cfg(not(target_os = "android"))]
-    let _ = font_handle;
     entity_id
 }
 
@@ -1013,15 +1007,11 @@ fn update_card_entity(
             ));
         });
     }
-    #[cfg(target_os = "android")]
-    if card_images.is_some() {
+    if USE_TOUCH_UI_LAYOUT && card_images.is_some() {
         commands.entity(entity).with_children(|b| {
             add_android_corner_label(b, card, layout.card_size, color_blind, high_contrast, font_handle);
         });
     }
-    // Suppress unused-variable warning when not building for Android.
-    #[cfg(not(target_os = "android"))]
-    let _ = font_handle;
 }
 
 fn label_for(card: &Card) -> String {
@@ -1094,9 +1084,8 @@ fn label_visibility(card: &Card) -> Visibility {
     }
 }
 
-/// Rank+suit string for the Android readability overlay.
+/// Rank+suit string for the readability overlay on touch HUD layouts.
 /// Uses Unicode suit glyphs (♠♥♦♣ — U+2660–U+2666, covered by FiraMono).
-#[cfg(target_os = "android")]
 fn mobile_label_for(card: &Card) -> String {
     let rank = match card.rank {
         Rank::Ace => "A",
@@ -1132,7 +1121,6 @@ fn mobile_label_for(card: &Card) -> String {
 /// those glyphs, causing a coloured missing-glyph rectangle to appear in
 /// the text colour — the root cause of the "red square on face-down cards"
 /// visual bug (the box bleeds through near the card edge at z=0.02).
-#[cfg(target_os = "android")]
 fn add_android_corner_label(
     parent: &mut ChildSpawnerCommands,
     card: &Card,
@@ -2146,15 +2134,11 @@ fn resize_cards_in_place(
 /// change or any window resize). The full despawn/respawn path in
 /// `update_card_entity` already handles game-state changes; this system
 /// covers the resize-only path where children are mutated in place.
-#[cfg(target_os = "android")]
 fn resize_android_corner_labels(
     layout: Res<LayoutResource>,
     card_images: Option<Res<CardImageSet>>,
     mut text_query: Query<(&AndroidCornerLabel, &mut Text2d, &mut TextFont, &mut Transform)>,
-    mut bg_query: Query<
-        (&mut Sprite, &mut Transform),
-        (With<AndroidCornerBg>, Without<AndroidCornerLabel>),
-    >,
+    mut bg_query: Query<(&mut Sprite, &mut Transform), AndroidCornerBgFilter>,
 ) {
     if !layout.is_changed() || card_images.is_none() {
         return;