Phase 25: division leaderboard, market trade history

- Market: record buy/sell history in market_history table; expose via
  GET /market/trade-history (last 30 events, newest first)
- Division: GET /division/leaderboard returns 10-club table with 9 seeded
  NPC entries + player row, sorted by pts; stable within a season
- rand feature small_rng enabled in Cargo.toml for SmallRng use
- 3 new integration tests (leaderboard count, sort order, empty trade history)
- Core: 96 tests passing

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

src/services/market.rs

@@ -160,14 +160,37 @@ pub async fn buy_listing(
     .execute(pool)
     .await?;
 
-    card_db
+    let card = card_db
         .get(&listing.card_id)
         .cloned()
-        .ok_or_else(|| AppError::NotFound("card definition not found".into()))
+        .ok_or_else(|| AppError::NotFound("card definition not found".into()))?;
+
+    // Record trade history (best-effort — never abort the buy on failure)
+    let _ = sqlx::query(
+        "INSERT INTO market_history (id, club_id, card_id, card_name, card_overall, \
+         trade_type, price, traded_at) VALUES (?,?,?,?,?,?,?,?)",
+    )
+    .bind(Uuid::new_v4().to_string())
+    .bind(club_id)
+    .bind(&card.id)
+    .bind(&card.name)
+    .bind(card.overall as i64)
+    .bind("buy")
+    .bind(listing.price)
+    .bind(chrono::Utc::now().to_rfc3339())
+    .execute(pool)
+    .await;
+
+    Ok(card)
 }
 
-pub async fn sell_card(pool: &Pool, club_id: &str, req: &SellCardRequest) -> AppResult<i64> {
-    let _owned = sqlx::query_as::<_, crate::models::card::OwnedCard>(
+pub async fn sell_card(
+    pool: &Pool,
+    card_db: &CardDb,
+    club_id: &str,
+    req: &SellCardRequest,
+) -> AppResult<i64> {
+    let owned = sqlx::query_as::<_, crate::models::card::OwnedCard>(
         "SELECT id, club_id, card_id, is_loan, loan_matches_remaining, acquired_at, \
          chemistry_style, position_override, training_bonus \
          FROM owned_cards WHERE id = ? AND club_id = ?",
@@ -185,9 +208,54 @@ pub async fn sell_card(pool: &Pool, club_id: &str, req: &SellCardRequest) -> App
 
     let coins = (req.price as f64 * 0.4) as i64;
     let new_balance = club::add_coins(pool, club_id, coins).await?;
+
+    // Record trade history
+    if let Some(card) = card_db.get(&owned.card_id) {
+        let _ = sqlx::query(
+            "INSERT INTO market_history (id, club_id, card_id, card_name, card_overall, \
+             trade_type, price, traded_at) VALUES (?,?,?,?,?,?,?,?)",
+        )
+        .bind(Uuid::new_v4().to_string())
+        .bind(club_id)
+        .bind(&card.id)
+        .bind(&card.name)
+        .bind(card.overall as i64)
+        .bind("sell")
+        .bind(coins)
+        .bind(chrono::Utc::now().to_rfc3339())
+        .execute(pool)
+        .await;
+    }
+
     Ok(new_balance)
 }
 
+/// Return the last 30 buy/sell events for this club, newest first.
+pub async fn get_trade_history(pool: &Pool, club_id: &str) -> AppResult<Vec<serde_json::Value>> {
+    let rows = sqlx::query(
+        "SELECT card_name, card_overall, trade_type, price, traded_at \
+         FROM market_history WHERE club_id = ? ORDER BY traded_at DESC LIMIT 30",
+    )
+    .bind(club_id)
+    .fetch_all(pool)
+    .await?;
+
+    use sqlx::Row;
+    let trades = rows
+        .iter()
+        .map(|r| {
+            serde_json::json!({
+                "card_name":    r.get::<String, _>("card_name"),
+                "card_overall": r.get::<i64, _>("card_overall"),
+                "trade_type":   r.get::<String, _>("trade_type"),
+                "price":        r.get::<i64, _>("price"),
+                "traded_at":    r.get::<String, _>("traded_at"),
+            })
+        })
+        .collect();
+    Ok(trades)
+}
+
 fn price_for_card(overall: u8) -> i64 {
     match overall {
         85..=u8::MAX => 50_000,