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/layout.rs

@@ -269,7 +269,10 @@ pub fn compute_layout(
             5 => Tableau::Tableau6,
             _ => Tableau::Tableau7,
         };
-        pile_positions.insert(KlondikePile::Tableau(tableau), Vec2::new(col_x(i), tableau_y));
+        pile_positions.insert(
+            KlondikePile::Tableau(tableau),
+            Vec2::new(col_x(i), tableau_y),
+        );
     }
 
     // Adaptive tableau fan fraction. On height-limited (desktop) windows the
@@ -339,7 +342,9 @@ mod tests {
             Tableau::Tableau7,
         ] {
             assert!(
-                layout.pile_positions.contains_key(&KlondikePile::Tableau(tableau)),
+                layout
+                    .pile_positions
+                    .contains_key(&KlondikePile::Tableau(tableau)),
                 "missing tableau {tableau:?}"
             );
         }
@@ -758,7 +763,11 @@ mod tests {
         let window = Vec2::new(360.0, 800.0);
         let without = compute_layout(window, 0.0, 0.0, true);
         let with_inset = compute_layout(window, 0.0, 48.0, true);
-        for pile in [KlondikePile::Stock, KlondikePile::Tableau(Tableau::Tableau1), KlondikePile::Tableau(Tableau::Tableau7)] {
+        for pile in [
+            KlondikePile::Stock,
+            KlondikePile::Tableau(Tableau::Tableau1),
+            KlondikePile::Tableau(Tableau::Tableau7),
+        ] {
             assert!(
                 (without.pile_positions[&pile].x - with_inset.pile_positions[&pile].x).abs() < 1e-3,
                 "{pile:?} x-position must not change with safe_area_bottom",