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/receive_tab.cpp

@@ -13,6 +13,7 @@
 #include "../../config/settings.h"
 #include "../../util/i18n.h"
 #include "../../util/platform.h"
+#include "../../util/text_format.h"
 #include "../../config/version.h"
 #include "../../data/wallet_state.h"
 #include "../../ui/widgets/qr_code.h"
@@ -71,14 +72,6 @@ static bool s_generating_address = false;
 // ============================================================================
 // Helpers
 // ============================================================================
-static std::string TruncateAddress(const std::string& addr, size_t maxLen = 40) {
-    // Guard maxLen <= 3 before the unsigned (maxLen - 3): otherwise it wraps and the
-    // trailing substr(length - halfLen) throws std::out_of_range on short inputs.
-    if (maxLen <= 3 || addr.length() <= maxLen) return addr;
-    size_t halfLen = (maxLen - 3) / 2;
-    return addr.substr(0, halfLen) + "..." + addr.substr(addr.length() - halfLen);
-}
-
 static void OpenExplorerURL(App* app, const std::string& address) {
     std::string url = app->settings()->getAddressExplorerUrl() + address;
     dragonx::util::Platform::openUrl(url);
@@ -201,8 +194,8 @@ static void RenderAddressDropdown(App* app, float width) {
         const auto& addr = state.addresses[s_selected_address_idx];
         bool isZ = addr.type == "shielded";
         const char* tag = isZ ? "[Z]" : "[T]";
-        std::string trunc = TruncateAddress(addr.address,
-            static_cast<size_t>(std::max(schema::UI().drawElement("tabs.receive", "addr-preview-trunc-min").size, width / schema::UI().drawElement("tabs.receive", "addr-preview-trunc-divisor").size)));
+        std::string trunc = util::truncateMiddle(addr.address,
+            static_cast<int>(std::max(schema::UI().drawElement("tabs.receive", "addr-preview-trunc-min").size, width / schema::UI().drawElement("tabs.receive", "addr-preview-trunc-divisor").size)));
         snprintf(buf, sizeof(buf), "%s %s  \xe2\x80\x94  %.8f %s",
                  tag, trunc.c_str(), addr.balance, DRAGONX_TICKER);
         s_source_preview = buf;
@@ -258,7 +251,7 @@ static void RenderAddressDropdown(App* app, float width) {
                     auto lblIt = s_address_labels.find(addr.address);
                     bool hasLabel = (lblIt != s_address_labels.end() && !lblIt->second.empty());
 
-                    std::string trunc = TruncateAddress(addr.address, addrTruncLen);
+                    std::string trunc = util::truncateMiddle(addr.address, (int)addrTruncLen);
                     if (hasLabel) {
                         snprintf(buf, sizeof(buf), "%s %s (%s)  \xe2\x80\x94  %.8f %s%s",
                                  tag, lblIt->second.c_str(), trunc.c_str(),
@@ -304,10 +297,8 @@ static void RenderAddressDropdown(App* app, float width) {
     ImGui::SameLine(0, Layout::spacingSm());
     ImGui::BeginDisabled(!app->isConnected() || s_generating_address);
     if (s_generating_address) {
-        int dots = ((int)(ImGui::GetTime() * 3.0f)) % 4;
-        const char* dotStr[] = {"", ".", "..", "..."};
         char genLabel[64];
-        snprintf(genLabel, sizeof(genLabel), "%s%s##recv", TR("generating"), dotStr[dots]);
+        snprintf(genLabel, sizeof(genLabel), "%s%s##recv", TR("generating"), material::LoadingDots());
         TactileButton(genLabel, ImVec2(newBtnW, 0), schema::UI().resolveFont("button"));
     } else if (TactileButton(TrId("new", "recv").c_str(), ImVec2(newBtnW, 0), schema::UI().resolveFont("button"))) {
         s_generating_address = true;
@@ -418,8 +409,8 @@ static void RenderRecentReceived(const AddressInfo& /* addr */,
 
         // Address (second line)
         float addrX = txX + S.drawElement("tabs.balance", "recent-tx-addr-offset").sizeOr(65.0f);
-        std::string addrDisplay = TruncateAddress(tx.address,
-            (size_t)S.drawElement("tabs.balance", "recent-tx-addr-trunc").sizeOr(20.0f));
+        std::string addrDisplay = util::truncateMiddle(tx.address,
+            (int)S.drawElement("tabs.balance", "recent-tx-addr-trunc").sizeOr(20.0f));
         rowDL->AddText(capFont, capFont->LegacySize,
                        ImVec2(addrX, rowPos.y + 2.0f * dp), OnSurfaceDisabled(), addrDisplay.c_str());