Phase 18: data expansion and market pricing fix

Four new card files (Serie A, Ligue 1, Primeira Liga, Eredivisie) add 45
cards across Italian, French, Portuguese, and Dutch football, bringing the
total card pool from 115 to 160. Each file uses fictional club/player
names and null image_path, keeping the project free of copyrighted assets.

Ten new SBC challenges (league_sbcs.json) targeting specific leagues and
nations increase the total from 7 to 17 challenges. Includes league purity
SBCs (Premier League, Bundesliga, Serie A, Ligue 1, Eredivisie), nation
combo SBCs (Iberian Derby, South American Fire), and utility SBCs (elite
strikers mini-submission, bronze-to-silver recycler, world tour).

NPC market refresh now shuffles the card pool before picking 24 listings
(was: take first 20 unshuffled), and price variance tightened from ±100%
to ±25% of the OVR-tier base price for more realistic NPC competition.

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

data/cards/serie_a.json

@@ -0,0 +1,17 @@
+[
+  {"id":"card_sa_001","name":"Lorenzo Ricci","overall":87,"position":"ST","nation":"Italy","league":"Serie A","club":"Roma Capitale FC","pace":83,"shooting":90,"passing":72,"dribbling":84,"defending":32,"physical":85,"rarity":"raregold","image_path":null},
+  {"id":"card_sa_002","name":"Marco Ferretti","overall":85,"position":"CAM","nation":"Italy","league":"Serie A","club":"Milano Azzurri","pace":80,"shooting":82,"passing":88,"dribbling":87,"defending":40,"physical":72,"rarity":"raregold","image_path":null},
+  {"id":"card_sa_003","name":"Davide Conti","overall":83,"position":"CB","nation":"Italy","league":"Serie A","club":"Napoli Sud FC","pace":72,"shooting":45,"passing":68,"dribbling":65,"defending":87,"physical":84,"rarity":"gold","image_path":null},
+  {"id":"card_sa_004","name":"Emanuele Vitali","overall":82,"position":"CM","nation":"Italy","league":"Serie A","club":"Roma Capitale FC","pace":74,"shooting":70,"passing":84,"dribbling":80,"defending":68,"physical":76,"rarity":"gold","image_path":null},
+  {"id":"card_sa_005","name":"Filippo Marchetti","overall":84,"position":"GK","nation":"Italy","league":"Serie A","club":"Milano Azzurri","pace":55,"shooting":20,"passing":58,"dribbling":30,"defending":85,"physical":82,"rarity":"gold","image_path":null},
+  {"id":"card_sa_006","name":"Gianluca Russo","overall":81,"position":"LB","nation":"Italy","league":"Serie A","club":"Torino Granata","pace":82,"shooting":52,"passing":74,"dribbling":76,"defending":80,"physical":74,"rarity":"gold","image_path":null},
+  {"id":"card_sa_007","name":"Alessandro Greco","overall":80,"position":"RB","nation":"Italy","league":"Serie A","club":"Napoli Sud FC","pace":84,"shooting":55,"passing":72,"dribbling":74,"defending":78,"physical":72,"rarity":"gold","image_path":null},
+  {"id":"card_sa_008","name":"Federico Palermo","overall":82,"position":"CDM","nation":"Italy","league":"Serie A","club":"Torino Granata","pace":70,"shooting":58,"passing":76,"dribbling":72,"defending":84,"physical":82,"rarity":"gold","image_path":null},
+  {"id":"card_sa_009","name":"Simone Bianchi","overall":79,"position":"RW","nation":"Italy","league":"Serie A","club":"Roma Capitale FC","pace":88,"shooting":76,"passing":72,"dribbling":82,"defending":38,"physical":65,"rarity":"gold","image_path":null},
+  {"id":"card_sa_010","name":"Roberto Neri","overall":78,"position":"LW","nation":"Italy","league":"Serie A","club":"Milano Azzurri","pace":86,"shooting":74,"passing":70,"dribbling":80,"defending":35,"physical":62,"rarity":"gold","image_path":null},
+  {"id":"card_sa_011","name":"Matteo De Luca","overall":77,"position":"CB","nation":"Italy","league":"Serie A","club":"Napoli Sud FC","pace":68,"shooting":40,"passing":62,"dribbling":60,"defending":80,"physical":80,"rarity":"gold","image_path":null},
+  {"id":"card_sa_012","name":"Claudio Esposito","overall":76,"position":"ST","nation":"Italy","league":"Serie A","club":"Torino Granata","pace":80,"shooting":78,"passing":62,"dribbling":74,"defending":28,"physical":76,"rarity":"gold","image_path":null},
+  {"id":"card_sa_013","name":"Nicolás Peralta","overall":83,"position":"ST","nation":"Argentina","league":"Serie A","club":"Roma Capitale FC","pace":82,"shooting":86,"passing":70,"dribbling":82,"defending":30,"physical":80,"rarity":"gold","image_path":null},
+  {"id":"card_sa_014","name":"Henrique Sousa","overall":80,"position":"CAM","nation":"Brazil","league":"Serie A","club":"Milano Azzurri","pace":82,"shooting":76,"passing":82,"dribbling":86,"defending":42,"physical":68,"rarity":"gold","image_path":null},
+  {"id":"card_sa_015","name":"Sven Holm","overall":75,"position":"CM","nation":"Sweden","league":"Serie A","club":"Napoli Sud FC","pace":72,"shooting":65,"passing":78,"dribbling":74,"defending":70,"physical":72,"rarity":"gold","image_path":null}
+]