style: aplicar fixes de clang-tidy (todo excepto uppercase-literal-suffix)

Corregidos ~2570 issues automáticamente con clang-tidy --fix-errors
más ajustes manuales posteriores:

- modernize: designated-initializers, trailing-return-type, use-auto,
  avoid-c-arrays (→ std::array<>), use-ranges, use-emplace,
  deprecated-headers, use-equals-default, pass-by-value,
  return-braced-init-list, use-default-member-init
- readability: math-missing-parentheses, implicit-bool-conversion,
  braces-around-statements, isolate-declaration, use-std-min-max,
  identifier-naming, else-after-return, redundant-casting,
  convert-member-functions-to-static, make-member-function-const,
  static-accessed-through-instance
- performance: avoid-endl, unnecessary-value-param, type-promotion,
  inefficient-vector-operation
- dead code: XOR_KEY (orphan tras eliminar encryptData/decryptData),
  dead stores en engine.cpp y png_shape.cpp
- NOLINT justificado en 10 funciones con alta complejidad cognitiva
  (initialize, render, main, processEvents, update×3, performDemoAction,
  randomizeOnDemoStart, renderDebugHUD, AppLogo::update)

Compilación: gcc -Wall sin warnings. clang-tidy: 0 issues.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

source/gpu/gpu_ball_buffer.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <SDL3/SDL_gpu.h>
+
 #include <cstdint>
 
 // ---------------------------------------------------------------------------
@@ -12,9 +13,9 @@
 //   r,g,b,a: RGBA in [0,1]
 // ---------------------------------------------------------------------------
 struct BallGPUData {
-    float cx, cy;      // NDC center
-    float hw, hh;      // NDC half-size (positive)
-    float r, g, b, a;  // RGBA color [0,1]
+        float cx, cy;      // NDC center
+        float hw, hh;      // NDC half-size (positive)
+        float r, g, b, a;  // RGBA color [0,1]
 };
 static_assert(sizeof(BallGPUData) == 32, "BallGPUData must be 32 bytes");
 
@@ -26,22 +27,21 @@ static_assert(sizeof(BallGPUData) == 32, "BallGPUData must be 32 bytes");
 //   // Then in render pass: bind buffer, SDL_DrawGPUPrimitives(pass, 6, count, 0, 0)
 // ============================================================================
 class GpuBallBuffer {
-public:
-    static constexpr int MAX_BALLS = 500000;
+    public:
+        static constexpr int MAX_BALLS = 500000;
 
-    bool init(SDL_GPUDevice* device);
-    void destroy(SDL_GPUDevice* device);
+        bool init(SDL_GPUDevice* device);
+        void destroy(SDL_GPUDevice* device);
 
-    // Upload ball array to GPU via an internal copy pass.
-    // count is clamped to MAX_BALLS.  Returns false on error or empty input.
-    bool upload(SDL_GPUDevice* device, SDL_GPUCommandBuffer* cmd,
-                const BallGPUData* data, int count);
+        // Upload ball array to GPU via an internal copy pass.
+        // count is clamped to MAX_BALLS.  Returns false on error or empty input.
+        bool upload(SDL_GPUDevice* device, SDL_GPUCommandBuffer* cmd, const BallGPUData* data, int count);
 
-    SDL_GPUBuffer* buffer() const { return gpu_buf_; }
-    int count() const { return count_; }
+        SDL_GPUBuffer* buffer() const { return gpu_buf_; }
+        int count() const { return count_; }
 
-private:
-    SDL_GPUBuffer*         gpu_buf_      = nullptr;
-    SDL_GPUTransferBuffer* transfer_buf_ = nullptr;
-    int                    count_        = 0;
+    private:
+        SDL_GPUBuffer* gpu_buf_ = nullptr;
+        SDL_GPUTransferBuffer* transfer_buf_ = nullptr;
+        int count_ = 0;
 };