Fixed warnings by improving ISO C compliance

[lazzy-cipher]

This PR fixes the following warnings I get when using Clay+Raylib with GCC 15.2.1 and with -Wall, -Wextra, and -pedantic enabled:

Changes done:

• Replaced initializer braces {} and { 0 } with CLAY__DEFAULT_STRUCT
• Remove extra trailing semicolon in struct definition
• Cast signed int to uint32_t in comparison to fix signedness mismatch
• Added /* fall through */ comment to suppress the implicit case fallthrough warning
• Removed unused variables
• Cast unused parameters to (void)

clay.h:3071:50: warning: ISO C forbids empty initializer braces before C23 [-Wpedantic]
 3071 |             Clay_Dimensions contentSizeCurrent = {};
      |                                                  ^

clay.h:160:79: warning: ISO C forbids empty initializer braces before C23 [-Wpedantic]
  160 | #define CLAY__CONFIG_WRAPPER(type, ...) (CLAY__INIT(CLAY__WRAPPER_TYPE(type)) { __VA_ARGS__ }).wrapped
      |                                                                               ^
clay.h:3313:21: note: in expansion of macro ‘CLAY_AUTO_ID’
 3313 |                     CLAY_AUTO_ID() {
      |                     ^~~~~~~~~~~~

clay.h: In function ‘Clay__RenderDebugView’:
clay.h:3635:72: warning: ISO C forbids empty initializer braces before C23 [-Wpedantic]
 3635 |                     CLAY(CLAY_ID("Clay__DebugViewElementInfoPadding"), { }) {
      |

clay.h:3739:84: warning: ISO C forbids empty initializer braces before C23 [-Wpedantic]
 3739 |                             CLAY(CLAY_ID("Clay__DebugViewElementInfoAspectRatio"), { }) {
      |                                                                                    ^

clay.h:4369:2: warning: ISO C does not allow extra ‘;’ outside of a function [-Wpedantic]
 4369 | };
      |  ^

clay.h:4484:114: warning: comparison of integer expressions of different signedness: ‘int’ and ‘uint32_t’ {aka ‘unsigned int’} [-Wsign-compare]
 4484 |                             if (config->exit.siblingOrdering == CLAY_EXIT_TRANSITION_ORDERING_NATURAL_ORDER && j == data->siblingIndex) {
      |

clay_renderer_raylib.c:235:31: warning: ISO C forbids empty initializer braces before C23 [-Wpedantic]
  235 |                     (Vector2) {},
      |                               ^

clay.h:2257:54: warning: unused parameter ‘deltaTime’ [-Wunused-parameter]
 2257 | void Clay__SizeContainersAlongAxis(bool xAxis, float deltaTime, Clay__int32_tArray* textElementsOut, Clay__int32_tArray* aspectRatioElementsOut) {
      |                                                ~~~~~~^~~~~~~~~

clay.h: In function ‘Clay__CalculateFinalLayout’:
clay.h:3114:48: warning: unused variable ‘childMapItem’ [-Wunused-variable]
 3114 |                 Clay_LayoutElementHashMapItem* childMapItem = Clay__GetHashMapItem(childElement->id);
      |                                                ^~~~~~~~~~~~

clay.h: In function ‘Clay__DebugViewRenderElementConfigHeader’:
clay.h:3449:59: warning: unused parameter ‘elementId’ [-Wunused-parameter]
 3449 | void Clay__DebugViewRenderElementConfigHeader(Clay_String elementId, Clay__DebugElementConfigType type) {
      |                                               ~~~~~~~~~~~~^~~~~~~~~

clay.h: In function ‘Clay__CloneElementsWithExitTransition’:
clay.h:4360:41: warning: unused variable ‘newChildElement’ [-Wunused-variable]
 4360 |                     Clay_LayoutElement* newChildElement = Clay_LayoutElementArray_Set_DontTouchLength(&context->layoutElements, nextIndex, *childElement);
      |                                         ^~~~~~~~~~~~~~~

clay.h:4343:39: warning: unused variable ‘config’ [-Wunused-variable]
 4343 |         Clay_TransitionElementConfig* config = &data->elementThisFrame->config.transition;
      |                                       ^~~~~~

[rats159]

Should also explicitly use void in 0-parameter functions, looks like Clay__CloneElementsWithExitTransition is the only real function that has this issue. there's also a fully empty Clay__CreateDebugView function which has the issue.

Also, Clay_LayoutElement uses an anonymous union and anonymous struct which is C11. This looks harder to fix though, unfortunately.

[lazzy-cipher]

Should also explicitly use void in 0-parameter functions, looks like Clay__CloneElementsWithExitTransition is the only real function that has this issue. there's also a fully empty Clay__CreateDebugView function which has the issue.

Also, Clay_LayoutElement uses an anonymous union and anonymous struct which is C11. This looks harder to fix though, unfortunately.

While non-void 0 parameter functions don't give warnings in most compilers, I added void to the parameters of Clay_GetLayoutDimensions() and Clay__CloneElementsWithExitTransition().

Also, I fixed the merge conflicts.

[erasmussen1]

Looks good