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/lib.rs

@@ -1,13 +1,16 @@
 //! Bevy integration layer for Ferrous Solitaire.
 
 pub mod achievement_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod analytics_plugin;
 #[cfg(target_os = "android")]
 pub mod android_clipboard;
 pub mod animation_plugin;
 pub mod assets;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod audio_plugin;
 pub mod auto_complete_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod avatar_plugin;
 pub mod card_animation;
 pub mod card_plugin;
@@ -26,6 +29,7 @@ pub mod home_plugin;
 pub mod hud_plugin;
 pub mod input_plugin;
 pub mod layout;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod leaderboard_plugin;
 pub mod onboarding_plugin;
 pub mod pause_plugin;
@@ -43,7 +47,9 @@ pub mod selection_plugin;
 pub mod settings_plugin;
 pub mod splash_plugin;
 pub mod stats_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod sync_plugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub mod sync_setup_plugin;
 pub mod table_plugin;
 pub mod theme;
@@ -57,14 +63,17 @@ pub mod weekly_goals_plugin;
 pub mod win_summary_plugin;
 
 pub use achievement_plugin::{AchievementPlugin, AchievementsResource, AchievementsScreen};
+#[cfg(not(target_arch = "wasm32"))]
 pub use analytics_plugin::{AnalyticsPlugin, AnalyticsResource};
 pub use animation_plugin::{ActiveToast, AnimationPlugin, CardAnim, ToastEntity, ToastQueue};
 pub use assets::{
     AssetSourcesPlugin, DARK_THEME_MANIFEST_URL, USER_THEMES, bundled_theme_url,
     populate_embedded_dark_theme, register_theme_asset_sources,
 };
+#[cfg(not(target_arch = "wasm32"))]
 pub use audio_plugin::{AudioPlugin, AudioState, SoundLibrary};
 pub use auto_complete_plugin::AutoCompletePlugin;
+#[cfg(not(target_arch = "wasm32"))]
 pub use avatar_plugin::{AvatarFetchEvent, AvatarPlugin, AvatarResource};
 pub use card_animation::{
     AnimationChain, AnimationTuning, BufferedInput, CardAnimation, CardAnimationPlugin,
@@ -117,6 +126,7 @@ pub use hud_plugin::{
 };
 pub use input_plugin::InputPlugin;
 pub use layout::{Layout, LayoutResource, compute_layout};
+#[cfg(not(target_arch = "wasm32"))]
 pub use leaderboard_plugin::{LeaderboardPlugin, LeaderboardResource, LeaderboardScreen};
 pub use onboarding_plugin::{OnboardingPlugin, OnboardingScreen};
 pub use pause_plugin::{ForfeitConfirmScreen, PausePlugin, PauseScreen, PausedResource};
@@ -155,7 +165,9 @@ pub use stats_plugin::{
     ReplaySelectorCaption, SelectedReplayIndex, StatsPlugin, StatsResource, StatsScreen,
     StatsUpdate, WatchReplayButton, format_replay_caption,
 };
+#[cfg(not(target_arch = "wasm32"))]
 pub use sync_plugin::{SyncPlugin, SyncProviderResource};
+#[cfg(not(target_arch = "wasm32"))]
 pub use sync_setup_plugin::SyncSetupPlugin;
 pub use table_plugin::{
     BackgroundImageSet, HintPileHighlight, PileMarker, TableBackground, TablePlugin,