feat(web): add solitaire_web Bevy WASM build targeting play.html canvas

Adds a new `solitaire_web` crate that compiles the full `solitaire_engine`
to `wasm32-unknown-unknown` and renders to a `<canvas id="bevy-canvas">`
element in `play.html` — the same ECS code path as desktop and Android.

Changes to enable the WASM target:
- .cargo/config.toml: add wasm32-unknown-unknown rustflags for getrandom
- Workspace Cargo.toml: add solitaire_web member
- solitaire_data/Cargo.toml: gate tokio/reqwest/dirs/keyring to non-wasm
- solitaire_data/src: add wasm32 branch to data_dir() (returns None);
  cfg-gate sync_client network types, auth_tokens, matomo_client
- solitaire_engine/Cargo.toml: gate tokio/reqwest/kira/arboard/dirs/zip
  to non-wasm (mio/cpal/arboard don't compile for wasm32-unknown-unknown)
- solitaire_engine/src/lib.rs: cfg-gate module declarations and re-exports
  for analytics, audio, sync, sync_setup, avatar, leaderboard plugins
- solitaire_engine/src/core_game_plugin.rs: cfg-gate plugin registrations
  that require TokioRuntime (audio, sync, analytics, leaderboard, avatar)
- solitaire_engine/src/resources.rs: cfg-gate TokioRuntimeResource
- solitaire_engine/src/game_plugin.rs: cfg-gate std::fs::remove_file (x10)
- solitaire_engine/src/theme/mod.rs: cfg-gate importer module (uses dirs+zip)
- solitaire_engine/src/settings_plugin.rs: cfg-gate theme ZIP import UI
- solitaire_engine/src/assets/sources.rs: cfg-gate FileAssetReader/user_theme_dir
- solitaire_engine/src/auto_complete_plugin.rs: cfg-gate audio system
- solitaire_engine/src/daily_challenge_plugin.rs: cfg-gate server fetch
- solitaire_engine/src/hud_plugin.rs: cfg-gate AvatarResource import
- solitaire_engine/src/profile_plugin.rs: cfg-gate AvatarResource import
- solitaire_server/web/play.html: minimal HTML canvas shell
- solitaire_web/: new crate (Cargo.toml + src/lib.rs)
- build_wasm.sh: add Bevy WASM build step (cargo + wasm-bindgen + wasm-opt)

All tests pass; clippy --workspace -- -D warnings clean; native build
(solitaire_engine, solitaire_app) unaffected.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/core_game_plugin.rs

@@ -13,16 +13,18 @@ use crate::platform::{
     default_storage_backend,
 };
 use crate::{
-    AchievementPlugin, AnalyticsPlugin, AnimationPlugin, AssetSourcesPlugin, AudioPlugin,
-    AutoCompletePlugin, AvatarPlugin, CardAnimationPlugin, CardPlugin, ChallengePlugin,
-    CursorPlugin, DailyChallengePlugin, DiagnosticsHudPlugin, DifficultyPlugin, FeedbackAnimPlugin,
-    FontPlugin, GamePlugin, HelpPlugin, HomePlugin, HudPlugin, InputPlugin, LeaderboardPlugin,
-    OnboardingPlugin, PausePlugin, PlayBySeedPlugin, ProfilePlugin, ProgressPlugin,
-    RadialMenuPlugin, ReplayOverlayPlugin, ReplayPlaybackPlugin, SafeAreaInsetsPlugin,
-    SelectionPlugin, SettingsPlugin, SplashPlugin, StatsPlugin, SyncPlugin, SyncProvider,
-    SyncSetupPlugin, TablePlugin, ThemePlugin, ThemeRegistryPlugin, TimeAttackPlugin,
-    TouchSelectionPlugin, UiFocusPlugin, UiModalPlugin, UiTooltipPlugin, WeeklyGoalsPlugin,
-    WinSummaryPlugin,
+    AchievementPlugin, AnimationPlugin, AssetSourcesPlugin, AutoCompletePlugin,
+    CardAnimationPlugin, CardPlugin, ChallengePlugin, CursorPlugin, DailyChallengePlugin,
+    DiagnosticsHudPlugin, DifficultyPlugin, FeedbackAnimPlugin, FontPlugin, GamePlugin, HelpPlugin,
+    HomePlugin, HudPlugin, InputPlugin, OnboardingPlugin, PausePlugin, PlayBySeedPlugin,
+    ProfilePlugin, ProgressPlugin, RadialMenuPlugin, ReplayOverlayPlugin, ReplayPlaybackPlugin,
+    SafeAreaInsetsPlugin, SelectionPlugin, SettingsPlugin, SplashPlugin, StatsPlugin, SyncProvider,
+    TablePlugin, ThemePlugin, ThemeRegistryPlugin, TimeAttackPlugin, TouchSelectionPlugin,
+    UiFocusPlugin, UiModalPlugin, UiTooltipPlugin, WeeklyGoalsPlugin, WinSummaryPlugin,
+};
+#[cfg(not(target_arch = "wasm32"))]
+use crate::{
+    AnalyticsPlugin, AudioPlugin, AvatarPlugin, LeaderboardPlugin, SyncPlugin, SyncSetupPlugin,
 };
 
 /// Groups all Ferrous Solitaire gameplay plugins.
@@ -45,6 +47,7 @@ impl Plugin for CoreGamePlugin {
             Ok(guard) => guard,
             Err(poisoned) => poisoned.into_inner(),
         };
+        #[cfg_attr(target_arch = "wasm32", allow(unused_variables))]
         let sync_provider = sync_provider
             .take()
             .expect("CoreGamePlugin::build called twice");
@@ -104,21 +107,26 @@ impl Plugin for CoreGamePlugin {
             .add_plugins(HudPlugin)
             .add_plugins(HelpPlugin)
             .add_plugins(HomePlugin::default())
-            .add_plugins(AvatarPlugin)
             .add_plugins(ProfilePlugin)
             .add_plugins(PausePlugin)
             .add_plugins(SettingsPlugin::default())
-            .add_plugins(AudioPlugin)
             .add_plugins(OnboardingPlugin)
-            .add_plugins(SyncPlugin::new(sync_provider))
-            .add_plugins(SyncSetupPlugin)
-            .add_plugins(AnalyticsPlugin)
-            .add_plugins(LeaderboardPlugin)
             .add_plugins(WinSummaryPlugin)
             .add_plugins(UiModalPlugin)
             .add_plugins(UiFocusPlugin)
             .add_plugins(UiTooltipPlugin)
             .add_plugins(SplashPlugin)
             .add_plugins(DiagnosticsHudPlugin);
+
+        // Plugins that use kira/cpal audio or multi-threaded Tokio are not
+        // compatible with the single-threaded wasm32 runtime.  Gate them out
+        // so the browser build boots silently and without a sync backend.
+        #[cfg(not(target_arch = "wasm32"))]
+        app.add_plugins(AvatarPlugin)
+            .add_plugins(AudioPlugin)
+            .add_plugins(SyncPlugin::new(sync_provider))
+            .add_plugins(SyncSetupPlugin)
+            .add_plugins(AnalyticsPlugin)
+            .add_plugins(LeaderboardPlugin);
     }
 }