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/main.cpp

@@ -1,8 +1,9 @@
-#include <iostream>
 #include <cstring>
+#include <iostream>
 #include <string>
-#include "engine.hpp"
+
 #include "defines.hpp"
+#include "engine.hpp"
 #include "resource_manager.hpp"
 
 // getExecutableDirectory() ya está definido en defines.h como inline
@@ -38,7 +39,7 @@ void printHelp() {
     std::cout << "Nota: Si resolución > pantalla, se usa default. Zoom se ajusta automáticamente.\n";
 }
 
-int main(int argc, char* argv[]) {
+auto main(int argc, char* argv[]) -> int {  // NOLINT(readability-function-cognitive-complexity)
     int width = 0;
     int height = 0;
     int zoom = 0;
@@ -58,7 +59,8 @@ int main(int argc, char* argv[]) {
         if (strcmp(argv[i], "--help") == 0) {
             printHelp();
             return 0;
-        } else if (strcmp(argv[i], "-w") == 0 || strcmp(argv[i], "--width") == 0) {
+        }
+        if (strcmp(argv[i], "-w") == 0 || strcmp(argv[i], "--width") == 0) {
             if (i + 1 < argc) {
                 width = atoi(argv[++i]);
                 if (width < 320) {
@@ -189,25 +191,29 @@ int main(int argc, char* argv[]) {
 
     Engine engine;
 
-    if (custom_balls > 0)
+    if (custom_balls > 0) {
         engine.setCustomScenario(custom_balls);  // pre-init: asigna campos antes del benchmark
+    }
 
-    if (max_balls_override > 0)
+    if (max_balls_override > 0) {
         engine.setMaxBallsOverride(max_balls_override);
-    else if (skip_benchmark)
+    } else if (skip_benchmark) {
         engine.setSkipBenchmark();
+    }
 
-    if (initial_postfx >= 0)
+    if (initial_postfx >= 0) {
         engine.setInitialPostFX(initial_postfx);
+    }
 
     if (override_vignette >= 0.f || override_chroma >= 0.f) {
-        if (initial_postfx < 0)
+        if (initial_postfx < 0) {
             engine.setInitialPostFX(0);
+        }
         engine.setPostFXParamOverrides(override_vignette, override_chroma);
     }
 
     if (!engine.initialize(width, height, zoom, fullscreen, initial_mode)) {
-        std::cout << "¡Error al inicializar el engine!" << std::endl;
+        std::cout << "¡Error al inicializar el engine!" << '\n';
         return -1;
     }