Implement full MVP: auth, HD wallet, Electrum client, deposits, bets, round/draw engine, payout, withdrawals, RBF, admin+audit

All 10 build-order stages complete and unit-tested (49 tests). Verified live on
mainnet: registration/address derivation, deposit crediting, a real 10 PLM bet
(broadcast + confirmed + change credited). A full round close->draw->payout
cycle was triggered live and was in progress at commit time. Withdrawal and RBF
bump are unit-tested but not yet exercised against a live broadcast. Known gaps
(scheduler doesn't resume mid-flight rounds after restart, payout has no retry,
no deployment setup, etc.) are documented in CLAUDE.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/auth/security.py

@@ -0,0 +1,31 @@
+from datetime import datetime, timedelta, timezone
+
+import jwt
+from argon2 import PasswordHasher
+from argon2.exceptions import VerifyMismatchError
+
+from app.config import settings
+
+_hasher = PasswordHasher()
+
+
+def hash_password(password: str) -> str:
+    return _hasher.hash(password)
+
+
+def verify_password(password: str, password_hash: str) -> bool:
+    try:
+        return _hasher.verify(password_hash, password)
+    except VerifyMismatchError:
+        return False
+
+
+def create_access_token(user_id: int) -> str:
+    expires_at = datetime.now(timezone.utc) + timedelta(minutes=settings.jwt_expire_minutes)
+    payload = {"sub": str(user_id), "exp": expires_at}
+    return jwt.encode(payload, settings.jwt_secret, algorithm=settings.jwt_algorithm)
+
+
+def decode_access_token(token: str) -> int:
+    payload = jwt.decode(token, settings.jwt_secret, algorithms=[settings.jwt_algorithm])
+    return int(payload["sub"])