feat(engine): wire AnimSpeed to animation, new achievements, leaderboard opt-in, daily goal display

- AnimSpeed setting now drives card slide duration (Normal=0.15s, Fast=0.07s, Instant=snap);
  EffectiveSlideDuration resource updated on SettingsChangedEvent; AnimSpeed row added to Settings panel
- GameState.recycle_count tracks waste recycles; perfectionist/comeback/zen_winner achievements added
  with full unit tests
- SyncProvider gains opt_in_leaderboard(); SolitaireServerClient implements POST /api/leaderboard/opt-in;
  Opt In button added to leaderboard panel
- DailyChallengeResource stores goal_description/target_score/max_time_secs from server;
  pressing C shows goal description as toast (DailyGoalAnnouncementEvent)

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

solitaire_core/src/game_state.rs

@@ -80,6 +80,10 @@ pub struct GameState {
     /// Number of times `undo()` has been successfully invoked this game.
     /// Used by achievement conditions like `no_undo`.
     pub undo_count: u32,
+    /// Number of times the waste pile has been recycled back to stock this game.
+    /// Used by the `comeback` achievement condition.
+    #[serde(default)]
+    pub recycle_count: u32,
     undo_stack: VecDeque<StateSnapshot>,
 }
 
@@ -116,6 +120,7 @@ impl GameState {
             is_won: false,
             is_auto_completable: false,
             undo_count: 0,
+            recycle_count: 0,
             undo_stack: VecDeque::new(),
         }
     }
@@ -167,6 +172,7 @@ impl GameState {
                 card.face_up = false;
                 stock.cards.push(card);
             }
+            self.recycle_count = self.recycle_count.saturating_add(1);
             return Ok(());
         }
 
@@ -481,6 +487,24 @@ mod tests {
         assert!(g.piles[&PileType::Waste].cards.is_empty());
     }
 
+    #[test]
+    fn recycle_count_increments_on_each_waste_recycle() {
+        let mut g = new_game();
+        assert_eq!(g.recycle_count, 0);
+        // Drain entire stock to waste.
+        while !g.piles[&PileType::Stock].cards.is_empty() {
+            g.draw().unwrap();
+        }
+        g.draw().unwrap(); // first recycle
+        assert_eq!(g.recycle_count, 1);
+        // Drain again and recycle a second time.
+        while !g.piles[&PileType::Stock].cards.is_empty() {
+            g.draw().unwrap();
+        }
+        g.draw().unwrap(); // second recycle
+        assert_eq!(g.recycle_count, 2);
+    }
+
     #[test]
     fn draw_from_empty_stock_and_waste_returns_error() {
         // The only stop condition for draw() is: both stock AND waste are