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_data/src/settings.rs

@@ -49,7 +49,7 @@ pub enum SyncBackend {
     #[default]
     #[serde(rename = "local")]
     Local,
-    /// Sync with a self-hosted Solitaire Quest server.
+    /// Sync with a self-hosted Ferrous Solitaire server.
     #[serde(rename = "solitaire_server")]
     SolitaireServer {
         /// Base URL of the server, e.g. `"https://solitaire.example.com"`.