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/theme/registry.rs

@@ -22,9 +22,9 @@
 use std::path::Path;
 
 use bevy::log::warn;
-use bevy::prelude::{App, Plugin, Resource};
 #[cfg(not(target_arch = "wasm32"))]
 use bevy::prelude::Startup;
+use bevy::prelude::{App, Plugin, Resource};
 use serde::Deserialize;
 
 use super::ThemeMeta;