refactor(wallet): split 2321-LOC god-file into app.wallet package (P3B.2)

Move app/wallet_manager_v2.py verbatim to app/wallet/manager.py with a
thin WalletManagerFacade class wrapper exposing the public API.

The legacy app/wallet_manager_v2.py becomes a 19-line re-export shim.
Public API preserved (WalletManagerV2, get_wallet_manager_v2, all
enums/records/helpers). Routes unchanged (56).

Phase 3B of AUDIT-2026-Q3.md.

app/wallet/__init__.py

@@ -0,0 +1,25 @@
+"""Wallet subsystem.
+
+Phase 3B of AUDIT-2026-Q3.md.
+
+Re-exports the canonical public API of WalletManagerV2. The bulk of the
+implementation lives in app.wallet.manager (moved verbatim from
+app.wallet_manager_v2 on 2026-07-07).
+"""
+from app.wallet.manager import (  # noqa: F401
+    ChainMeta,
+    PaymentRecord,
+    PaymentType,
+    ShamirSecretSharing,
+    WalletEncryption,
+    WalletManagerFacade,
+    WalletManagerV2,
+    WalletPurpose,
+    WalletRecord,
+    WalletRotationSchedule,
+    WalletStatus,
+    WalletTier,
+    ZKAddressVerifier,
+    get_wallet_manager_v2,
+    import_legacy_wallets,
+)