refactor: fase 4 — llista enllaçada de Momia a std::vector<unique_ptr>

Eliminada completament la recursivitat per next-pointer:
- Momia::next, clear(), insertar() desapareixen
- update()/draw() no recursen: operen només sobre la instància pròpia
- ModuleGame::momies: Momia* (head de llista) → std::vector<std::unique_ptr<Momia>>
  - Destructor simplificat (vector s'autodestrueix)
  - Draw: range-for sobre el vector
  - Update: std::erase_if + decrement sincronitzat de info::ctx.momies
  - Cheat "alone": momies.clear()
  - iniciarMomies i nova_momia: emplace_back(std::make_unique<Momia>(...))

Zero new/delete manuals al cicle de vida de les momies.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

source/game/momia.hpp

@@ -1,25 +1,22 @@
-#pragma once
-
-#include <memory>
-
-#include "game/engendro.hpp"
-#include "game/info.hpp"
-#include "game/prota.hpp"
-#include "game/sprite.hpp"
-
-class Momia : public Sprite {
-   public:
-    explicit Momia(JD8_Surface gfx, bool dimoni, Uint16 x, Uint16 y, Prota* sam);
-
-    void clear();
-    void draw() override;
-    bool update();
-    void insertar(Momia* momia);
-
-    bool dimoni;
-    Momia* next;
-
-   protected:
-    Prota* sam;
-    std::unique_ptr<Engendro> engendro;
-};
+#pragma once
+
+#include <memory>
+
+#include "game/engendro.hpp"
+#include "game/info.hpp"
+#include "game/prota.hpp"
+#include "game/sprite.hpp"
+
+class Momia : public Sprite {
+   public:
+    explicit Momia(JD8_Surface gfx, bool dimoni, Uint16 x, Uint16 y, Prota* sam);
+
+    void draw() override;
+    bool update();
+
+    bool dimoni;
+
+   protected:
+    Prota* sam;
+    std::unique_ptr<Engendro> engendro;
+};