chore: add alert about release plans when cloning flag (#10802)

https://linear.app/unleash/issue/2-3966/cloning-a-feature-will-not-clone-release-plans

Adds an alert when cloning a feature flag with a release plan.

Requires the `featureReleasePlans` feature flag.

<img width="1162" height="568" alt="image"
src="https://github.com/user-attachments/assets/325db586-14b9-4ce4-9d7c-6f680017c6ac"
/>

Author: nunogois

frontend/src/component/feature/CopyFeature/CopyFeature.tsx

@@ -78,6 +78,9 @@ export const CopyFeatureToggle = () => {
     const navigate = useNavigate();
     const { isChangeRequestConfiguredInAnyEnv } =
         useChangeRequestsEnabled(projectId);
+    const hasReleasePlan = feature.environments?.some((env) =>
+        Boolean(env.releasePlans?.length),
+    );
 
     const {
         project: { featureNaming },
@@ -146,6 +149,16 @@ export const CopyFeatureToggle = () => {
                     </StyledAlert>
                 }
             />
+            <ConditionallyRender
+                condition={hasReleasePlan}
+                show={
+                    <StyledAlert severity='warning'>
+                        Cloning a feature flag will not clone the associated
+                        release plans. You will need to set up a new release
+                        plan for the cloned feature flag.
+                    </StyledAlert>
+                }
+            />
             <StyledSection>
                 <StyledDescription>
                     You are about to create a new feature flag by cloning the