[VDS] Cache mana symbol renders and skip redundant resizes (#7167)

* [VDS] Cache mana symbol renders and skip redundant resizes

- Render each mana symbol once at a bounded master size and derive every
  requested size from the cached master, avoiding repeated full-size SVG
  rasterization on the GUI thread
- Share scaled results through a process-wide cache keyed by symbol and
  size, so repeated widget creation and rescales don't redo the work
- Skip redundant resize work in ColorIdentityWidget and ManaSymbolWidget
  when sizes did not change

Took 8 minutes


Took 50 seconds

* Move to pixmap generator

Took 8 minutes

Took 4 seconds

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/widgets/utility/card_completer_delegate.h

@@ -31,9 +31,6 @@ public:
     QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const override;
 
 private:
-    // Mana symbol pixmaps, loaded once and cached
-    mutable QCache<QString, QPixmap> symbolCache;
-
     // Set short codes, resolved once per card name and cached
     mutable QCache<QString, QString> setCodeCache;
 
@@ -47,9 +44,6 @@ private:
     // adventure costs ("1W // W") are drawn as separate groups. Returns the left-most x used
     int drawManaCost(QPainter *p, const QRect &row, const QString &manaCost, int radius) const;
 
-    // Load (or return cached) a mana icon pixmap; falls back to painted circle
-    const QPixmap *cachedSymbolPixmap(const QString &symbol, int size) const;
-
     // Resolve the preferred printing's set short code for a card
     QString setCodeForCard(const QSharedPointer<CardInfo> &card) const;