Add DrawCircleGradientV: Vector2 variant for gradient circles

Fixes issue #5738 - DrawCircleGradient doesn't have a Vector2 variant.

This adds DrawCircleGradientV() function that accepts a Vector2 center parameter,
making it usable with Camera and small world-space coordinates.

The implementation follows the same delegation pattern as other circle functions:
- DrawCircle() delegates to DrawCircleV()
- DrawCircleLines() delegates to DrawCircleLinesV()
- DrawCircleGradient() now delegates to DrawCircleGradientV()

This maintains API consistency across all circle drawing functions.

src/raylib.h

@@ -1282,6 +1282,7 @@ RLAPI void DrawCircle(int centerX, int centerY, float radius, Color color);
 RLAPI void DrawCircleSector(Vector2 center, float radius, float startAngle, float endAngle, int segments, Color color);      // Draw a piece of a circle
 RLAPI void DrawCircleSectorLines(Vector2 center, float radius, float startAngle, float endAngle, int segments, Color color); // Draw circle sector outline
 RLAPI void DrawCircleGradient(int centerX, int centerY, float radius, Color inner, Color outer);         // Draw a gradient-filled circle
+RLAPI void DrawCircleGradientV(Vector2 center, float radius, Color inner, Color outer);                  // Draw a gradient-filled circle (Vector version)
 RLAPI void DrawCircleV(Vector2 center, float radius, Color color);                                       // Draw a color-filled circle (Vector version)
 RLAPI void DrawCircleLines(int centerX, int centerY, float radius, Color color);                         // Draw circle outline
 RLAPI void DrawCircleLinesV(Vector2 center, float radius, Color color);                                  // Draw circle outline (Vector version)

src/rshapes.c

@@ -475,16 +475,22 @@ void DrawCircleSectorLines(Vector2 center, float radius, float startAngle, float
 
 // Draw a gradient-filled circle
 void DrawCircleGradient(int centerX, int centerY, float radius, Color inner, Color outer)
+{
+    DrawCircleGradientV((Vector2){ (float)centerX, (float)centerY }, radius, inner, outer);
+}
+
+// Draw a gradient-filled circle (Vector version)
+void DrawCircleGradientV(Vector2 center, float radius, Color inner, Color outer)
 {
     rlBegin(RL_TRIANGLES);
         for (int i = 0; i < 360; i += 10)
         {
             rlColor4ub(inner.r, inner.g, inner.b, inner.a);
-            rlVertex2f((float)centerX, (float)centerY);
+            rlVertex2f(center.x, center.y);
             rlColor4ub(outer.r, outer.g, outer.b, outer.a);
-            rlVertex2f((float)centerX + cosf(DEG2RAD*(i + 10))*radius, (float)centerY + sinf(DEG2RAD*(i + 10))*radius);
+            rlVertex2f(center.x + cosf(DEG2RAD*(i + 10))*radius, center.y + sinf(DEG2RAD*(i + 10))*radius);
             rlColor4ub(outer.r, outer.g, outer.b, outer.a);
-            rlVertex2f((float)centerX + cosf(DEG2RAD*i)*radius, (float)centerY + sinf(DEG2RAD*i)*radius);
+            rlVertex2f(center.x + cosf(DEG2RAD*i)*radius, center.y + sinf(DEG2RAD*i)*radius);
         }
     rlEnd();
 }