chore: rename app from Solitaire Quest to Ferrous Solitaire

Replace all display-name occurrences across web pages, Rust source,
docs, and Cargo metadata. Update localStorage token key from sq_token
to fs_token. Tagline "Klondike Solitaire" retained as genre descriptor.

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

solitaire_engine/src/theme/registry.rs

@@ -115,7 +115,7 @@ fn default_entry() -> ThemeEntry {
         meta: ThemeMeta {
             id: "default".to_string(),
             name: "Default".to_string(),
-            author: "Solitaire Quest".to_string(),
+            author: "Ferrous Solitaire".to_string(),
             version: "1.0".to_string(),
             card_aspect: (2, 3),
         },