feat: add Spotlight sidecar for local Sentry development testing

Add the Spotlight container to compose.override.yaml so the feedback
widget and error events can be inspected locally without sending anything
to Sentry. The JS SDK switches to spotlight mode automatically when no
SENTRY_DSN is configured.

compose.override.yaml

@@ -70,5 +70,10 @@ services:
       MP_SMTP_AUTH_ALLOW_INSECURE: 1
   ###< symfony/mailer ###
 
+  spotlight:
+    image: ghcr.io/getsentry/spotlight:latest
+    ports:
+      - "8969:8969"
+
 volumes:
   sass: