style(core): apply cargo fmt across routes, services, models, tests

Pure rustfmt reflow (import grouping, array/match-arm/call-arg wrapping,
alphabetized module decls, comment realignment). No semantic change:
full-diff and `git diff -w` both confirm logic byte-identical to 271c363;
workspace builds and all 74 core tests pass. Retained pre-existing WIP
brought forward after verification.

src/services/pack.rs

@@ -73,14 +73,13 @@ pub async fn open_pack(
 
     // Atomically claim the pack before minting any cards: only one concurrent opener
     // flips opened 0->1, so a double-open cannot mint the reward twice (duplication).
-    let claimed = sqlx::query(
-        "UPDATE packs SET opened = 1 WHERE id = ? AND club_id = ? AND opened = 0",
-    )
-    .bind(pack_id)
-    .bind(club_id)
-    .execute(pool)
-    .await?
-    .rows_affected();
+    let claimed =
+        sqlx::query("UPDATE packs SET opened = 1 WHERE id = ? AND club_id = ? AND opened = 0")
+            .bind(pack_id)
+            .bind(club_id)
+            .execute(pool)
+            .await?
+            .rows_affected();
     if claimed == 0 {
         return Err(AppError::BadRequest("pack already opened".into()));
     }
@@ -134,8 +133,8 @@ pub async fn open_pack(
         }
     }
 
-    let card_ids_json = serde_json::to_string(&cards.iter().map(|c| &c.id).collect::<Vec<_>>())
-        .unwrap_or_default();
+    let card_ids_json =
+        serde_json::to_string(&cards.iter().map(|c| &c.id).collect::<Vec<_>>()).unwrap_or_default();
     let now = chrono::Utc::now().to_rfc3339();
 
     sqlx::query("UPDATE packs SET opened_cards = ?, opened_at = ? WHERE id = ?")