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/manifest.rs

@@ -84,7 +84,7 @@ mod tests {
         ThemeMeta {
             id: "default".into(),
             name: "Default".into(),
-            author: "Solitaire Quest".into(),
+            author: "Ferrous Solitaire".into(),
             version: "1.0.0".into(),
             card_aspect: (2, 3),
         }