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>

tests/unit/test_hd.py

@@ -0,0 +1,21 @@
+from embit.bip32 import HDKey
+
+from app.wallet.plm_network import PLM_MAINNET
+
+
+def test_p2wpkh_address_uses_plm_hrp():
+    from embit import script
+
+    root = HDKey.from_seed(b"\x01" * 32, version=PLM_MAINNET["xprv"])
+    child = root.derive("m/84h/746h/0h/0/0")
+    address = script.p2wpkh(child.to_public()).address(network=PLM_MAINNET)
+    assert address.startswith("plm1q")
+
+
+def test_derivation_is_deterministic():
+    root = HDKey.from_seed(b"\x02" * 32, version=PLM_MAINNET["xprv"])
+    a = root.derive("m/84h/746h/0h/0/5").sec()
+    b = root.derive("m/84h/746h/0h/0/5").sec()
+    c = root.derive("m/84h/746h/0h/0/6").sec()
+    assert a == b
+    assert a != c