Initial commit: OpenFUT Core

Offline Ultimate Team backend — game-independent REST API.

- 19 API endpoints: auth, profiles, clubs, cards, packs, squads,
  objectives, SBCs, match rewards, NPC market, statistics
- Axum + SQLite + SQLx with full migrations
- Weighted pack generator, SBC validation engine
- JSON-driven mod data (cards, packs, objectives, SBCs)
- 5 integration tests passing

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

data/cards/loan_icons.json

@@ -0,0 +1,19 @@
+[
+  {
+    "id": "card_icon_loan_001",
+    "name": "The Maestro (Loan)",
+    "overall": 94,
+    "position": "CAM",
+    "nation": "France",
+    "league": "Icons",
+    "club": "Icons",
+    "pace": 82,
+    "shooting": 88,
+    "passing": 95,
+    "dribbling": 92,
+    "defending": 60,
+    "physical": 72,
+    "rarity": "icon",
+    "image_path": null
+  }
+]