feat(market): per-group configurable price data

Each portfolio group can now configure how it is valued and which price
fields its card shows:

- Price basis: Market · USD, Market · BTC, DRGX only, or Manual (a custom
  price-per-DRGX + currency label). Manual mode values the group independently
  of the live DRGX market price.
- Field toggles: show DRGX amount / show value / show 24h change (24h enabled
  only for the live-market bases; value disabled for DRGX-only).
- The editor's left "Appearance" column gains a Price section (basis combo,
  manual price + currency inputs, field checkboxes); the live preview and the
  group cards both render through one pfBuildDisplay() helper so they stay in
  sync. Defaults preserve the prior behavior (DRGX + USD).

Persisted in settings.json (price_basis / manual_price / manual_currency /
show_drgx / show_value / show_24h).

Note: "price source per exchange/pair" is limited to USD/BTC/Manual — the app
only fetches the aggregate DRGX price (USD + BTC); ExchangePair carries no
price, so valuing against an arbitrary pair's live price would need a new
market fetch (can be added separately).

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

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

src/config/settings.h

@@ -80,6 +80,15 @@ public:
         std::vector<std::string> addresses;
         std::string icon;           // project_icons wallet-icon name; empty = no icon
         unsigned int color = 0;     // packed IM_COL32 accent; 0 = theme default
+        // Per-group price data. priceBasis: 0 = live market (USD), 1 = live market (BTC),
+        // 2 = DRGX only (no fiat value), 3 = manual price. Defaults preserve prior behavior
+        // (show DRGX + USD value).
+        int priceBasis = 0;
+        double manualPrice = 0.0;       // price per DRGX for the Manual basis
+        std::string manualCurrency = "USD";
+        bool showDrgx = true;           // show the DRGX amount on the card
+        bool showValue = true;          // show the converted/fiat value on the card
+        bool show24h = false;           // show the 24h % change (live-market bases only)
     };
 
     // Theme