feat: Phase 1 — core game loop complete

New endpoints:
- GET  /cards/:card_id       single card lookup
- POST /packs/buy            purchase pack with coins
- POST /objectives/claim     claim completed objective reward
- GET  /matches              match history (limit/mode query params)
- GET  /sbc/:sbc_id          single SBC lookup

Card pool expanded:
- Bronze: 11 → 30 cards (19 nations)
- Silver: 0 → 20 cards (20 nations)
- Rare Gold: 0 → 10 cards (10 nations)

SBC pool expanded:
- Added 5 new SBCs (tri_nations, silver_to_gold, league_loyalty,
  african_stars, gold_standard)

Infrastructure:
- SQLite WAL mode enabled on pool init
- Foreign key enforcement enabled

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

data/cards/rare_gold_sample.json

@@ -0,0 +1,12 @@
+[
+  { "id": "card_raregold_001", "name": "Gabriel Monteiro", "overall": 88, "position": "ST", "nation": "Brazil", "league": "Brasileirao", "club": "Flamengo", "pace": 92, "shooting": 89, "passing": 78, "dribbling": 87, "defending": 42, "physical": 82, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_002", "name": "Matteo Romano", "overall": 86, "position": "CAM", "nation": "Italy", "league": "Serie A", "club": "AS Roma", "pace": 79, "shooting": 84, "passing": 88, "dribbling": 87, "defending": 52, "physical": 70, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_003", "name": "Sven Bauer", "overall": 87, "position": "CB", "nation": "Germany", "league": "Bundesliga", "club": "Bayer Leverkusen", "pace": 82, "shooting": 44, "passing": 75, "dribbling": 72, "defending": 89, "physical": 88, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_004", "name": "Nicolás Paredes", "overall": 89, "position": "LW", "nation": "Argentina", "league": "Primera Division", "club": "Boca Juniors", "pace": 93, "shooting": 85, "passing": 82, "dribbling": 91, "defending": 45, "physical": 72, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_005", "name": "Antoine Mercier", "overall": 86, "position": "CM", "nation": "France", "league": "Ligue 1", "club": "Paris Saint-Germain", "pace": 80, "shooting": 78, "passing": 89, "dribbling": 84, "defending": 74, "physical": 76, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_006", "name": "Pedro Oliveira", "overall": 85, "position": "GK", "nation": "Portugal", "league": "Primeira Liga", "club": "Benfica", "pace": 52, "shooting": 15, "passing": 70, "dribbling": 48, "defending": 87, "physical": 82, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_007", "name": "Marcos Ibáñez", "overall": 87, "position": "RB", "nation": "Spain", "league": "La Liga", "club": "Atletico Madrid", "pace": 86, "shooting": 62, "passing": 80, "dribbling": 82, "defending": 87, "physical": 78, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_008", "name": "Samuel Osei", "overall": 86, "position": "CDM", "nation": "Ghana", "league": "Premier League", "club": "Chelsea", "pace": 78, "shooting": 65, "passing": 82, "dribbling": 78, "defending": 88, "physical": 86, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_009", "name": "Jin-Ho Lee", "overall": 85, "position": "RW", "nation": "South Korea", "league": "Bundesliga", "club": "RB Leipzig", "pace": 91, "shooting": 82, "passing": 78, "dribbling": 88, "defending": 43, "physical": 66, "rarity": "raregold", "image_path": null },
+  { "id": "card_raregold_010", "name": "Dmitri Volkov", "overall": 87, "position": "LB", "nation": "Russia", "league": "Premier League", "club": "Arsenal", "pace": 84, "shooting": 58, "passing": 82, "dribbling": 80, "defending": 88, "physical": 80, "rarity": "raregold", "image_path": null }
+]