feat(addresses): improve address labeling and view-only handling

- Add expanded address icon picker with search, bottom-aligned actions, and improved modal sizing
- Embed a pickaxe icon font subset and wire it into typography/address icon rendering
- Track view-only shielded addresses and prevent sends from non-spendable z-addresses
- Improve address transfer dialog sizing, max amount handling, and text clipping
- Tune main header layout values in ui.toml
- Update README, codebase overview, and third-party license documentation

src/ui/windows/send_tab.cpp

@@ -222,7 +222,7 @@ static void RenderSourceDropdown(App* app, float width) {
         int bestIdx = -1;
         double bestBal = 0.0;
         for (size_t i = 0; i < state.addresses.size(); i++) {
-            if (state.addresses[i].balance > bestBal) {
+            if (state.addresses[i].balance > bestBal && state.addresses[i].isSpendable()) {
                 bestBal = state.addresses[i].balance;
                 bestIdx = static_cast<int>(i);
             }
@@ -259,11 +259,11 @@ static void RenderSourceDropdown(App* app, float width) {
         if (!app->isConnected() || state.addresses.empty()) {
             ImGui::TextDisabled("%s", TR("no_addresses_available"));
         } else {
-            // Sort by balance descending, only show addresses with balance
+            // Sort by balance descending, only show spendable addresses with balance
             std::vector<size_t> sortedIdx;
             sortedIdx.reserve(state.addresses.size());
             for (size_t i = 0; i < state.addresses.size(); i++) {
-                if (state.addresses[i].balance > 0)
+                if (state.addresses[i].balance > 0 && state.addresses[i].isSpendable())
                     sortedIdx.push_back(i);
             }
             std::sort(sortedIdx.begin(), sortedIdx.end(),