feat(ui): layout polish — fill dead space, pair/box/collapse, warning weight, dialog glass

Implements the layout-improvement suggestions from the layout audit (visual arrangement
only; no functionality added or removed):

- Send/Receive: the recent-activity list now grows to fill the space below the fixed
  compose/receive card (more history visible), with a centered empty-state when there is
  none — instead of leaving dead canvas.
- Shield/Merge: pair the Fee and UTXO-Limit fields on one row to tighten vertical rhythm.
- Market: extend + frame the portfolio group-list as one contained panel (with a bottom
  edge) and center its empty-state, closing the previously un-anchored gap.
- Overlay dialogs: raise the card glass fill/border alpha (35/50 -> 60/90 of 255) so the
  dialog card reads as a distinct surface over busy backdrops (global, all overlays).
- Wallets: size the list height to the actual wallet count instead of always reserving 7
  rows, removing the large gap before the scan/create prompts (still scrolls when many).
- Contacts: width-aware address truncation shows more of the address on wide rows.
- Transfer Funds: give the "sends the full balance" warning a warning icon + color so the
  stakes stand out from the neutral result-preview lines.
- First-run wizard: collapse a completed Step 1 (Appearance) to the compact pill like
  Step 2, so a finished step is no longer taller than the active one.
- Explorer: distribute the Chain card's two stats to match the density of the sibling
  metrics grid.
- Validate Address: a "Results will appear here" caption fills the pre-interaction blank.
- Change Passphrase: add the warning banner its sibling security dialogs have.
- Migration ShowSeed: box the 24-word mnemonic grid (a GlassSectionScope behind the
  existing RenderSeedWordGrid) so the critical secret reads as a distinct artifact —
  purely visual, no seed/logic/state change.

Verified at 1280 across full-node + Lite + Windows (ctest green) and an adversarial diff
review (clean). New i18n key backfilled into all 8 languages.

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

src/ui/windows/shield_dialog.cpp

@@ -146,7 +146,10 @@ void ShieldDialog::render(App* app)
 
         ImGui::Spacing();
 
-        // Fee
+        // Fee + UTXO limit share one row (two columns) to tighten vertical rhythm.
+        float pairColX = ImGui::GetContentRegionAvail().x * 0.5f;
+
+        // Fee (left column)
         ImGui::Text("%s", TR("fee_label"));
         ImGui::SetNextItemWidth(feeInput.width * Layout::dpiScale());
         ImGui::InputDouble("##Fee", &s_fee, 0.0001, 0.001, "%.8f");
@@ -154,17 +157,19 @@ void ShieldDialog::render(App* app)
         if (s_fee > 1.0) s_fee = 1.0;          // guard a fat-fingered huge fee (mirrors utxo clamp)
         ImGui::SameLine();
         ImGui::TextDisabled("DRGX");
-        
-        ImGui::Spacing();
 
-        // UTXO limit
+        // UTXO limit (right column) — hint drops under the input (rather than beside it) since
+        // "Max UTXOs per operation" is too long to share the narrower half-width column with "DRGX".
+        ImGui::SameLine(pairColX);
+        ImGui::BeginGroup();
         ImGui::Text("%s", TR("shield_utxo_limit"));
         ImGui::SetNextItemWidth(utxoInput.width * Layout::dpiScale());
         ImGui::InputInt("##Limit", &s_utxo_limit);
-        ImGui::SameLine();
-        ImGui::TextDisabled("%s", TR("shield_max_utxos"));
         if (s_utxo_limit < 1) s_utxo_limit = 1;
         if (s_utxo_limit > 100) s_utxo_limit = 100;
+        material::Type().textColored(material::TypeStyle::Caption, material::OnSurfaceMedium(),
+            TR("shield_max_utxos"));
+        ImGui::EndGroup();
 
         ImGui::Spacing();