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/input/input_handler.hpp

@@ -24,7 +24,7 @@ class InputHandler {
          * @param engine Referencia al engine para ejecutar acciones
          * @return true si se debe salir de la aplicación (ESC o cerrar ventana), false en caso contrario
          */
-        bool processEvents(Engine& engine);
+        static bool processEvents(Engine& engine);
 
     private:
         // Sin estado interno por ahora - el InputHandler es stateless