refactor(mining): extract the Controls/CPU-grid card into mining_controls.{h,cpp} (audit #10, slice 3)

Third and largest slice of decomposing mining_tab.cpp. The ~843-line "Controls" card (CPU-core
grid + drag-to-select, mining start/stop button, benchmark + miner-update controls) is moved
verbatim into RenderMiningControls(). mining_tab.cpp is now 839 lines (was 2628 originally).

The most coupled section, so mutated state is passed BY REFERENCE — the benchmark
(ThreadBenchmark&), selected thread count (int&), and drag state (bool&/int&) — with local
reference aliases so the body stays byte-identical and interactions (drag, benchmark, start/stop)
behave exactly as before. Read-only context is passed by value/const; the compiler verified
const-correctness. Local statics inside the block moved with it.

Verified: full-node + Windows + lite build, tests, hygiene, no startup crash.

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

src/ui/windows/mining_controls.h

@@ -0,0 +1,32 @@
+// DragonX Wallet - ImGui Edition
+// Copyright 2024-2026 The Hush Developers
+// Released under the GPLv3
+
+#pragma once
+
+#include "../../data/wallet_state.h"
+#include "../material/draw_helpers.h"  // GlassPanelSpec
+#include "mining_benchmark.h"          // ThreadBenchmark
+#include "imgui.h"
+
+#include <string>
+
+namespace dragonx {
+class App;
+namespace ui {
+
+// Renders the mining "Controls" card (CPU-core grid + mining start/stop button + benchmark /
+// miner-update controls). Extracted verbatim from the monolithic mining tab. State the section
+// MUTATES is passed BY REFERENCE (the benchmark, selected thread count, and drag state) so the
+// interactions behave exactly as before; read-only context is passed by value/const.
+void RenderMiningControls(App* app, const WalletState& state, const MiningInfo& mining,
+                          ImDrawList* dl, ImFont* capFont, ImFont* sub1, ImFont* ovFont,
+                          float dp, float hs, float vs, float gap, float pad, float availWidth,
+                          const material::GlassPanelSpec& glassSpec, float controlsBudgetH,
+                          int max_threads, bool isMiningActive, bool poolMode,
+                          const char* poolWorker, const std::string& xmrigLatestTag,
+                          ThreadBenchmark& benchmark, int& selectedThreads,
+                          bool& dragActive, int& dragAnchorThread);
+
+} // namespace ui
+} // namespace dragonx