refactor(audit): batch 4 — UI design-system helpers + i18n

Mechanical, behavior-preserving consolidations from the audit. Rendering
extractions were kept byte-equivalent; sites that couldn't be made identical
were left as-is (noted below).

Shared helpers:
- util::truncateMiddle(s,maxLen) / (s,front,back) in text_format.h — replaces
  6 file-local middle-ellipsis truncators + several inline substr sites
  (send/receive/transactions/balance_recent_tx/explorer + app.cpp + 3 dialogs).
  Carries the maxLen<=3 guard, fixing the latent unsigned-underflow copies.
- material::LoadingDots() in draw_helpers.h — one animated-ellipsis source for
  8 copy-pasted spinner sites (identical GetTime()*3 phase preserved).
- Reuse the existing FormatHashrate() in explorer_tab + peers_tab (dropped two
  inline hashrate ladders).
- material::DrawButtonGlassOverlay() — the glass-fill/rim/tactile overlay block
  shared by TactileButton / TactileSmallButton / schema TactileButton.
- material::CollapsibleHeader() — the invisible-button + label + chevron idiom
  (3 of 5 settings_page sites; RPC/Debug headers skipped — non-identical).
- material::GlassCardScope (RAII) — the ChannelsSplit/Indent/DrawGlassPanel/
  ChannelsMerge card scaffold (5 settings_page cards; About/send/receive skipped
  — different padding / logo interleaving).
- material::DialogWarningHeader()/DialogConfirmFooter() — warning header +
  50/50 Cancel/danger footer across the confirm dialogs; button height moved
  from a hardcoded 40px into ui.toml (components.overlay-dialog.confirm-btn-height).
- File-local enterLowSpec()/exitLowSpec() collapse the 3 low-spec snapshot copies.

i18n: wrapped hardcoded English in the shared balance render paths and the
whole Lite lifecycle/security section in TR(), with English defaults added to
loadBuiltinEnglish() (res/lang/*.json left for the translation tooling — TR
falls back to English, so output is unchanged).

Full-node + Lite build clean; ctest 1/1; hygiene clean. These are rendering
changes — the Settings page (cards/headers/confirm dialogs), all tactile
buttons, and the Lite settings section warrant a screenshot check.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ui/windows/balance_components.cpp

@@ -200,10 +200,8 @@ void RenderSharedAddressList(App* app, float listH, float availW,
     bool sharedAddrSyncing = state.sync.syncing && !state.sync.isSynced();
     ImGui::BeginDisabled(sharedAddrSyncing);
     if (s_generating_z_address) {
-        int dots = ((int)(ImGui::GetTime() * 3.0f)) % 4;
-        const char* dotStr[] = {"", ".", "..", "..."};
         char genLabel[64];
-        snprintf(genLabel, sizeof(genLabel), "%s%s##shared_z", TR("generating"), dotStr[dots]);
+        snprintf(genLabel, sizeof(genLabel), "%s%s##shared_z", TR("generating"), material::LoadingDots());
         TactileButton(genLabel, ImVec2(buttonWidth, 0),
                       S.resolveFont(addrBtn.font.empty() ? "button" : addrBtn.font));
     } else if (TactileButton(TR("new_z_address"), ImVec2(buttonWidth, 0),
@@ -774,9 +772,9 @@ void RenderSharedRecentTx(App* app, float recentH, float availW, float hs, float
     const auto& state = app->state();
 
     ImGui::Dummy(ImVec2(0, Layout::spacingSm()));
-    Type().textColored(TypeStyle::Overline, OnSurfaceMedium(), "RECENT TRANSACTIONS");
+    Type().textColored(TypeStyle::Overline, OnSurfaceMedium(), TR("recent_transactions"));
     ImGui::SameLine();
-    if (TactileSmallButton("View All", S.resolveFont(actionBtn.font.empty() ? "button" : actionBtn.font))) {
+    if (TactileSmallButton(TR("view_all"), S.resolveFont(actionBtn.font.empty() ? "button" : actionBtn.font))) {
         app->setCurrentPage(NavPage::History);
     }
     ImGui::Spacing();
@@ -791,7 +789,7 @@ void RenderSharedRecentTx(App* app, float recentH, float availW, float hs, float
     int count = (int)txs.size();
 
     if (count == 0) {
-        Type().textColored(TypeStyle::Caption, OnSurfaceDisabled(), "No transactions yet");
+        Type().textColored(TypeStyle::Caption, OnSurfaceDisabled(), TR("no_transactions_yet"));
     } else {
         ImDrawList* dl = ImGui::GetWindowDrawList();
         ImFont* capFont = Type().caption();