LandingPage: Add Edge decommission alert (HMS-6156)

This alert will only be shown when the 'immutable' tab has focus.

src/Components/sharedComponents/ImageBuilderHeader.tsx

@@ -1,6 +1,7 @@
 import React, { useState } from 'react';
 
 import {
+  Alert,
   Button,
   Popover,
   Text,
@@ -21,6 +22,7 @@ import {
   CREATE_RHEL_IMAGES_WITH_AUTOMATED_MANAGEMENT_URL,
   CREATING_IMAGES_WITH_IB_SERVICE_URL,
   OSBUILD_SERVICE_ARCHITECTURE_URL,
+  RHEM_DOCUMENTATION_URL,
 } from '../../constants';
 import { useBackendPrefetch } from '../../store/backendApi';
 import { useAppSelector } from '../../store/hooks';
@@ -159,6 +161,44 @@ export const ImageBuilderHeader = ({
             </>
           )}
         </Flex>
+        {!isOnBlueprintsTab && (
+          <Flex>
+            <FlexItem>
+              <Alert
+                variant="info"
+                isInline
+                title={
+                  <>Upcoming decommission of hosted Edge Management service</>
+                }
+                className="pf-v5-u-mt-sm pf-v5-u-mb-sm"
+              >
+                <TextContent>
+                  <Text>
+                    As of July 31, 2025, the hosted edge management service will
+                    no longer be supported. This means that pushing image
+                    updates to Immutable (OSTree) systems using the Hybrid Cloud
+                    Console will be discontinued. For an alternative way to
+                    manage edge systems, customers are encouraged to explore Red
+                    Hat Edge Manager (RHEM).
+                  </Text>
+                  <Text>
+                    <Button
+                      component="a"
+                      target="_blank"
+                      variant="link"
+                      icon={<ExternalLinkAltIcon />}
+                      iconPosition="right"
+                      isInline
+                      href={RHEM_DOCUMENTATION_URL}
+                    >
+                      Red Hat Edge Manager (RHEM) documentation
+                    </Button>
+                  </Text>
+                </TextContent>
+              </Alert>
+            </FlexItem>
+          </Flex>
+        )}
       </PageHeader>
     </>
   );