feat(balance,notifications): shielded-card tooltip + clearer toast severity

- The Shielded balance card gains the explanatory hover tooltip the mining card
  already has (suppressed while the pending-chip tooltip is showing).
- Toasts get a severity-tinted background fill and a slightly thicker accent
  border, so Success/Warning/Error/Info differ by more than hue alone (the
  per-severity leading icon already existed). Tint opacity is a ui.toml token.

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

res/themes/ui.toml

@@ -1225,6 +1225,7 @@ pill-margin-y = { size = 3.0 }
 pill-rounding = { size = 12.0 }
 padding-x = { size = 12.0 }
 glass-fill-alpha = { size = 18.0 }
+accent-fill-alpha = { size = 0.22 }   # severity-tint fill opacity (fraction of the accent alpha)
 glass-border-alpha = { size = 35.0 }
 progress-bar-height = { size = 2.0 }
 duration-info = { size = 1.0 }

src/ui/notifications.cpp

@@ -123,9 +123,16 @@ void Notifications::render()
     glassSpec.borderWidth = 1.0f;
     material::DrawGlassPanel(dl, pMin, pMax, glassSpec);
 
+    // Severity-tinted fill so the toast differs by more than hue (helps when color alone is hard to read).
+    {
+        ImVec4 tint = accent_color;   // already premultiplied by fade `alpha`
+        tint.w *= nde("accent-fill-alpha", 0.22f);
+        dl->AddRectFilled(pMin, pMax, ImGui::ColorConvertFloat4ToU32(tint), pillRounding);
+    }
+
     // Colored accent border on top of the glass border for type indication
     ImU32 accentCol = ImGui::ColorConvertFloat4ToU32(accent_color);
-    dl->AddRect(pMin, pMax, accentCol, pillRounding, 0, 1.0f);
+    dl->AddRect(pMin, pMax, accentCol, pillRounding, 0, 1.5f * dp);
 
     // Progress bar at bottom of pill (accent-colored), clipped to pill rounded
     // corners.  Draw a full-pill-size rounded rect and clip it to just the

src/ui/windows/balance_tab.cpp

@@ -526,6 +526,7 @@ static void RenderBalanceClassic(App* app)
             }
 
             // Pending badge (top-right corner) — labeled so an unconfirmed "+X" doesn't read as a mystery.
+            bool pendingChipHovered = false;
             if (state.unconfirmed_balance > 0.0) {
                 snprintf(buf, sizeof(buf), TR("baltab_pending_chip"), state.unconfirmed_balance);
                 ImVec2 ts = capFont->CalcTextSizeA(
@@ -540,7 +541,7 @@ static void RenderBalanceClassic(App* app)
                 dl->AddText(capFont, capFont->LegacySize,
                             ImVec2(bMin.x + bp, bMin.y + bp * 0.5f),
                             amberCol, buf);
-                if (material::IsRectHovered(bMin, bMax)) material::Tooltip("%s", TR("baltab_pending_tip"));
+                if (material::IsRectHovered(bMin, bMax)) { pendingChipHovered = true; material::Tooltip("%s", TR("baltab_pending_tip")); }
             }
 
             // Hover glow + click to Receive
@@ -548,6 +549,7 @@ static void RenderBalanceClassic(App* app)
                 dl->AddRect(cMin, cMax, IM_COL32(255, 255, 255, (int)S.drawElement("tabs.balance", "hover-glow-alpha").sizeOr(40.0f)),
                             cardSpec.rounding, 0, S.drawElement("tabs.balance", "hover-glow-thickness").sizeOr(1.5f) * dp);
                 ImGui::SetMouseCursor(ImGuiMouseCursor_Hand);
+                if (!pendingChipHovered) material::Tooltip("%s", TR("shielded_card_tooltip"));
                 if (ImGui::IsMouseClicked(0))
                     app->setCurrentPage(NavPage::Receive);
             }