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_app/src/lib.rs

@@ -106,7 +106,7 @@ pub fn run() {
             DefaultPlugins
                 .set(WindowPlugin {
                     primary_window: Some(Window {
-                        title: "Solitaire Quest".into(),
+                        title: "Ferrous Solitaire".into(),
                         // X11/Wayland WM_CLASS so taskbar managers group
                         // multiple windows of this app correctly.
                         name: Some("solitaire-quest".into()),