fix(autofix): Show Add Integration CTA when no coding agents installed

The coding agent dropdown (which contains the 'Add Integration' link) was
only rendered when codingAgentOptions.length > 0. This meant orgs with zero
coding agent integrations had no way to discover or install one from the
autofix flow.

Change the guard to check whether codingAgentIntegrations is defined
(i.e. the step supports coding agents) rather than whether any exist,
so the dropdown with the CTA always appears on relevant steps.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Agent transcript: https://claudescope.sentry.dev/share/vM7qy1Z72d-FTlutPQFEXRVgHQcSlaKFH8eEv6_DB3M

Author: JoshFerge

static/app/components/events/autofix/v3/nextStep.tsx

@@ -342,7 +342,7 @@ function NextStepTemplate({
           <Button priority="primary" disabled={isProcessing} onClick={onClickYes}>
             {labelYes}
           </Button>
-          {codingAgentOptions?.length ? (
+          {codingAgentIntegrations === undefined ? null : (
             <DropdownMenu
               items={codingAgentOptions}
               trigger={(triggerProps, isOpen) => (
@@ -367,7 +367,7 @@ function NextStepTemplate({
                 </DropdownMenuFooter>
               }
             />
-          ) : null}
+          )}
         </ButtonBar>
       </Flex>
     </Flex>