style: aplicar checks modernize-* (215 fixes)

Cambios aplicados:
- [[nodiscard]] añadido a funciones que retornan valores
- .starts_with() en lugar de .find() == 0
- Inicializadores designados {.x=0, .y=0}
- auto en castings obvios
- = default para constructores triviales
- Funciones deleted movidas a public
- std::numbers::pi_v<float> (C++20)

Checks excluidos:
- use-trailing-return-type: Estilo controversial
- avoid-c-arrays: Arrays C aceptables en ciertos contextos

source/game/entities/bala.cpp

@@ -16,7 +16,7 @@
 
 Bala::Bala(SDL_Renderer* renderer)
     : renderer_(renderer),
-      centre_({0.0F, 0.0F}),
+      centre_({.x = 0.0F, .y = 0.0F}),
       angle_(0.0F),
       velocitat_(0.0F),
       esta_(false),
@@ -33,7 +33,7 @@ Bala::Bala(SDL_Renderer* renderer)
 void Bala::inicialitzar() {
     // Inicialment inactiva
     esta_ = false;
-    centre_ = {0.0F, 0.0F};
+    centre_ = {.x = 0.0F, .y = 0.0F};
     angle_ = 0.0F;
     velocitat_ = 0.0F;
     grace_timer_ = 0.0F;

source/game/entities/bala.hpp

@@ -22,10 +22,10 @@ class Bala {
         void dibuixar() const;
 
         // Getters (API pública sense canvis)
-        bool esta_activa() const { return esta_; }
-        const Punt& get_centre() const { return centre_; }
-        uint8_t get_owner_id() const { return owner_id_; }
-        float get_grace_timer() const { return grace_timer_; }
+        [[nodiscard]] bool esta_activa() const { return esta_; }
+        [[nodiscard]] const Punt& get_centre() const { return centre_; }
+        [[nodiscard]] uint8_t get_owner_id() const { return owner_id_; }
+        [[nodiscard]] float get_grace_timer() const { return grace_timer_; }
         void desactivar() { esta_ = false; }
 
     private:

source/game/entities/enemic.cpp

@@ -16,7 +16,7 @@
 
 Enemic::Enemic(SDL_Renderer* renderer)
     : renderer_(renderer),
-      centre_({0.0F, 0.0F}),
+      centre_({.x = 0.0F, .y = 0.0F}),
       angle_(0.0F),
       velocitat_(0.0F),
       drotacio_(0.0F),

source/game/entities/enemic.hpp

@@ -45,25 +45,25 @@ class Enemic {
         void dibuixar() const;
 
         // Getters (API pública sense canvis)
-        bool esta_actiu() const { return esta_; }
-        const Punt& get_centre() const { return centre_; }
-        const std::shared_ptr<Graphics::Shape>& get_forma() const { return forma_; }
+        [[nodiscard]] bool esta_actiu() const { return esta_; }
+        [[nodiscard]] const Punt& get_centre() const { return centre_; }
+        [[nodiscard]] const std::shared_ptr<Graphics::Shape>& get_forma() const { return forma_; }
         void destruir() { esta_ = false; }
-        float get_brightness() const { return brightness_; }
-        float get_drotacio() const { return drotacio_; }
-        Punt get_velocitat_vector() const {
+        [[nodiscard]] float get_brightness() const { return brightness_; }
+        [[nodiscard]] float get_drotacio() const { return drotacio_; }
+        [[nodiscard]] Punt get_velocitat_vector() const {
             return {
-                velocitat_ * std::cos(angle_ - (Constants::PI / 2.0F)),
-                velocitat_ * std::sin(angle_ - (Constants::PI / 2.0F))};
+                .x = velocitat_ * std::cos(angle_ - (Constants::PI / 2.0F)),
+                .y = velocitat_ * std::sin(angle_ - (Constants::PI / 2.0F))};
         }
 
         // Set ship position reference for tracking behavior
         void set_ship_position(const Punt* ship_pos) { ship_position_ = ship_pos; }
 
         // [NEW] Getters for stage system (base stats)
-        float get_base_velocity() const;
-        float get_base_rotation() const;
-        TipusEnemic get_tipus() const { return tipus_; }
+        [[nodiscard]] float get_base_velocity() const;
+        [[nodiscard]] float get_base_rotation() const;
+        [[nodiscard]] TipusEnemic get_tipus() const { return tipus_; }
 
         // [NEW] Setters for difficulty multipliers (stage system)
         void set_velocity(float vel) { velocitat_ = vel; }
@@ -74,8 +74,8 @@ class Enemic {
         void set_tracking_strength(float strength);
 
         // [NEW] Invulnerability queries
-        bool es_invulnerable() const { return timer_invulnerabilitat_ > 0.0F; }
-        float get_temps_invulnerabilitat() const { return timer_invulnerabilitat_; }
+        [[nodiscard]] bool es_invulnerable() const { return timer_invulnerabilitat_ > 0.0F; }
+        [[nodiscard]] float get_temps_invulnerabilitat() const { return timer_invulnerabilitat_; }
 
     private:
         SDL_Renderer* renderer_;
@@ -116,6 +116,6 @@ class Enemic {
         void comportament_pentagon(float delta_time);
         void comportament_quadrat(float delta_time);
         void comportament_molinillo(float delta_time);
-        float calcular_escala_actual() const;  // Returns scale with palpitation applied
+        [[nodiscard]] float calcular_escala_actual() const;  // Returns scale with palpitation applied
         bool intent_spawn_safe(const Punt& ship_pos, float& out_x, float& out_y);
 };

source/game/entities/nau.cpp

@@ -18,7 +18,7 @@
 
 Nau::Nau(SDL_Renderer* renderer, const char* shape_file)
     : renderer_(renderer),
-      centre_({0.0F, 0.0F}),
+      centre_({.x = 0.0F, .y = 0.0F}),
       angle_(0.0F),
       velocitat_(0.0F),
       esta_tocada_(false),

source/game/entities/nau.hpp

@@ -23,17 +23,17 @@ class Nau {
         void dibuixar() const;
 
         // Getters (API pública sense canvis)
-        const Punt& get_centre() const { return centre_; }
-        float get_angle() const { return angle_; }
-        bool esta_viva() const { return !esta_tocada_; }
-        bool esta_tocada() const { return esta_tocada_; }
-        bool es_invulnerable() const { return invulnerable_timer_ > 0.0F; }
-        const std::shared_ptr<Graphics::Shape>& get_forma() const { return forma_; }
-        float get_brightness() const { return brightness_; }
-        Punt get_velocitat_vector() const {
+        [[nodiscard]] const Punt& get_centre() const { return centre_; }
+        [[nodiscard]] float get_angle() const { return angle_; }
+        [[nodiscard]] bool esta_viva() const { return !esta_tocada_; }
+        [[nodiscard]] bool esta_tocada() const { return esta_tocada_; }
+        [[nodiscard]] bool es_invulnerable() const { return invulnerable_timer_ > 0.0F; }
+        [[nodiscard]] const std::shared_ptr<Graphics::Shape>& get_forma() const { return forma_; }
+        [[nodiscard]] float get_brightness() const { return brightness_; }
+        [[nodiscard]] Punt get_velocitat_vector() const {
             return {
-                velocitat_ * std::cos(angle_ - (Constants::PI / 2.0F)),
-                velocitat_ * std::sin(angle_ - (Constants::PI / 2.0F))};
+                .x = velocitat_ * std::cos(angle_ - (Constants::PI / 2.0F)),
+                .y = velocitat_ * std::sin(angle_ - (Constants::PI / 2.0F))};
         }
 
         // Setters