refactor(balance): extract shared rendering components into balance_components.{h,cpp} (audit #10)

First slice of decomposing balance_tab.cpp (3449 lines). The five rendering helpers used by every
balance layout — UpdateBalanceLerp, RenderCompactHero, RenderSharedAddressList (599 lines, the
drag-reorderable address list), RenderSharedRecentTx, RenderSyncBar — are moved verbatim into
balance_components.cpp. balance_tab.cpp is now 2680 lines.

Clean extraction: the helpers' interactive statics (drag/copy/hide/show) are function-local and
move WITH them; the only file-scope state they share is the balance-lerp animation values
(s_dispTotal/Shielded/Transparent/Unconfirmed) and s_generating_z_address, now non-static and
declared `extern` in balance_components.h (defined once in balance_tab.cpp, so both TUs share the
same objects). RenderCompactHero's default arg moved to the header declaration. The layouts (still
in balance_tab.cpp) call the helpers via the new header.

Verified: full-node + Windows + lite build (links cleanly -> extern state resolves), tests,
hygiene. This touches every layout's address list / recent-tx / hero / sync bar, so needs a
hands-on pass across the balance layouts before the next slice.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ui/windows/balance_components.h

@@ -0,0 +1,34 @@
+// DragonX Wallet - ImGui Edition
+// Copyright 2024-2026 The Hush Developers
+// Released under the GPLv3
+//
+// Shared rendering components used by every balance-tab layout (the animated hero, the address
+// list, the recent-transactions strip, the sync bar) plus the balance-lerp animation state.
+// Extracted from balance_tab.cpp so the layouts can be split into their own files later.
+
+#pragma once
+
+#include "imgui.h"
+
+namespace dragonx {
+class App;
+namespace ui {
+
+// Animated balance display values — lerp toward the wallet's real balances each frame. Defined in
+// balance_tab.cpp (the lerp is advanced by UpdateBalanceLerp), shared with the components.
+extern double s_dispTotal;
+extern double s_dispShielded;
+extern double s_dispTransparent;
+extern double s_dispUnconfirmed;
+// True while an async new-address generation is in flight.
+extern bool s_generating_z_address;
+
+void UpdateBalanceLerp(App* app);
+void RenderCompactHero(App* app, ImDrawList* dl, float availW, float hs, float vs,
+                       float heroHeightOverride = -1.0f);
+void RenderSharedAddressList(App* app, float listH, float availW, float glassRound, float hs, float vs);
+void RenderSharedRecentTx(App* app, float recentH, float availW, float hs, float vs);
+void RenderSyncBar(App* app, ImDrawList* dl, float vs);
+
+} // namespace ui
+} // namespace dragonx