fix(ui): consistent hashrate units, full-address tooltips, drop dead vars

- Balance card hashrate now uses the shared FormatHashrate() (TH/GH/MH/KH/H)
  instead of a bespoke two-tier KH/s formatter.
- Recent-tx rows show the full untruncated address on hover — two z-addresses can
  truncate to the same first/last window — and the truncate helpers guard maxLen<=3.
- Remove the unused viewTop/viewBot "viewport culling" locals in the tx list
  (pagination already bounds per-frame work).

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

src/ui/windows/balance_tab.cpp

@@ -6,6 +6,7 @@
 #include "balance_address_list.h"
 #include "balance_tab_helpers.h"
 #include "balance_recent_tx.h"
+#include "mining_tab_helpers.h"  // FormatHashrate (consistent MH/GH/.. scaling)
 #include "key_export_dialog.h"
 #include "qr_popup_dialog.h"
 #include "address_label_dialog.h"
@@ -430,10 +431,7 @@ static void RenderBalanceClassic(App* app)
                 dl->AddCircleFilled(ImVec2(cx + 4 * dp, cy + capFont->LegacySize * 0.5f),
                     S.drawElement("tabs.balance.classic", "mining-dot-radius").sizeOr(3.0f), mineCol);
                 double hr = state.mining.localHashrate;
-                if (hr >= 1000.0)
-                    snprintf(buf, sizeof(buf), "  Mining %.1f KH/s", hr / 1000.0);
-                else
-                    snprintf(buf, sizeof(buf), "  Mining %.0f H/s", hr);
+                snprintf(buf, sizeof(buf), "  Mining %s", FormatHashrate(hr).c_str());
                 dl->AddText(capFont, capFont->LegacySize,
                             ImVec2(cx + 12 * dp, cy),
                             WithAlpha(Success(), 200), buf);
@@ -1175,6 +1173,10 @@ static void RenderBalanceClassic(App* app)
                     dl->AddRectFilled(rowPos, rowEnd,
                                       IM_COL32(255, 255, 255, 15), S.drawElement("tabs.balance", "row-hover-rounding").sizeOr(4.0f));
                     ImGui::SetMouseCursor(ImGuiMouseCursor_Hand);
+                    // Show the full, untruncated address — two z-addresses can truncate to the
+                    // same first/last window, so the truncated text alone can't disambiguate.
+                    if (!tx.address.empty())
+                        ImGui::SetTooltip("%s", tx.address.c_str());
                     if (ImGui::IsMouseClicked(0))
                         app->setCurrentPage(NavPage::History);
                 }
@@ -3202,10 +3204,7 @@ static void RenderBalanceTwoRow(App* app) {
         }
         if (state.mining.generate) {
             double hr = state.mining.localHashrate;
-            if (hr >= 1000.0)
-                snprintf(buf, sizeof(buf), "Mining %.1f KH/s", hr / 1000.0);
-            else
-                snprintf(buf, sizeof(buf), "Mining %.0f H/s", hr);
+            snprintf(buf, sizeof(buf), "Mining %s", FormatHashrate(hr).c_str());
             Type().textColored(TypeStyle::Caption, WithAlpha(Success(), 200), buf);
             ImGui::SameLine();
         }