chore: cargo fmt across workspace; add analytics domain to CSP

- Apply cargo fmt to solitaire_engine, solitaire_server formatting.
- solitaire_server/src/lib.rs: add https://analytics.aleshym.co to
  script-src, img-src, and connect-src so the analytics beacon loads
  without a CSP violation.
- docs and README updates.

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

solitaire_engine/src/settings_plugin.rs

@@ -33,9 +33,9 @@ use crate::events::{
 use crate::font_plugin::FontResource;
 use crate::progress_plugin::ProgressResource;
 use crate::resources::{SettingsScrollPos, SyncStatus, SyncStatusResource};
-use crate::theme::{ThemeThumbnailCache, ThemeThumbnailPair};
 #[cfg(not(target_arch = "wasm32"))]
 use crate::theme::{ImportError, import_theme, refresh_registry};
+use crate::theme::{ThemeThumbnailCache, ThemeThumbnailPair};
 use crate::ui_focus::{FocusGroup, FocusRow, Focusable, FocusedButton};
 use crate::ui_modal::{
     ButtonVariant, ModalButton, ModalScrim, spawn_modal, spawn_modal_actions, spawn_modal_button,