feat(market): portfolio groups — PORTFOLIO heading, clickable cards, icon + color

- Rename the portfolio heading "MY DRGX" -> "PORTFOLIO".
- Group cards are now clickable: clicking one opens the editor directly on that
  group (edit mode), with a hover highlight + hand cursor.
- PortfolioEntry gains an `icon` (project_icons wallet-icon name) and a `color`
  (packed IM_COL32 accent); both are persisted in settings.json.
- Editor edit-mode gains an icon picker (the same wallet icon set as the overview
  tab's address-label dialog, via material::project_icons) with a "None" option,
  and a color picker (preset accent palette + a default/no-color swatch).
- Group cards render the chosen icon to the left of the name and, when a color
  is set, a left accent bar + the icon tinted in that color.

Full-node + Lite build clean; ctest 1/1; hygiene clean. Rendering change — needs
a screenshot check of the Market portfolio + the editor.

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

src/config/settings.cpp

@@ -314,6 +314,10 @@ bool Settings::load(const std::string& path)
                 if (e.contains("addresses") && e["addresses"].is_array())
                     for (const auto& a : e["addresses"])
                         if (a.is_string()) entry.addresses.push_back(a.get<std::string>());
+                if (e.contains("icon") && e["icon"].is_string())
+                    entry.icon = e["icon"].get<std::string>();
+                if (e.contains("color") && e["color"].is_number())
+                    entry.color = e["color"].get<unsigned int>();
                 if (!entry.label.empty()) portfolio_entries_.push_back(std::move(entry));
             }
         }
@@ -463,6 +467,8 @@ bool Settings::save(const std::string& path)
         entry["label"] = e.label;
         entry["addresses"] = json::array();
         for (const auto& a : e.addresses) entry["addresses"].push_back(a);
+        entry["icon"] = e.icon;
+        entry["color"] = e.color;
         j["portfolio_entries"].push_back(std::move(entry));
     }
     j["font_scale"]     = font_scale_;