fix: default dev environment fetches diagram data from download.reactome.org, not dev.reactome.org/download

GeneralService already had the right logic:

  download = computed(() =>
    environment.preferS3 && this.version.value()
      ? \`\${environment.s3}/\${this.version.value()}\`
      : DOWNLOAD)

but the default environment.ts (used by \`ng serve\` and by the dev
container that backs beta.reactome.org) had preferS3: false, so the
pathway-browser fetched diagram JSON from
dev.reactome.org/download/current/diagram/<stId>.json. That path is
behind mod_auth_openidc; the 302 to the Keycloak login was breaking
any non-authenticated visitor (and any cross-origin caller, since
the redirect doesn't carry CORS headers).

Flipping preferS3 to true routes through download.reactome.org/<v>/
which is the public CDN-style bucket -- same place every other env
already pointed at when the flag was on.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: adamjohnwright

projects/pathway-browser/src/environments/environment.ts

@@ -4,7 +4,7 @@ export const environment = {
   s3: "https://download.reactome.org",
   gsaServer: "dev",
   gtagId: "G-96F1EYHQR3",
-  preferS3: false,
+  preferS3: true,
 }
 
 export const CONTENT_SERVICE = `${environment.host}/ContentService`;