Fix discourse, moodle, supabase upgrades

- discourse 2026.10.0: skip assets:precompile in init container
  (assets are pre-built in 2026.x images, no git repo present)
  Re-enable slot 2026 as latest
- moodle: migrate from bitnamilegacy/moodle (EOL Aug 2025) to
  oksigenia/moodle:4.5 (drop-in replacement, same env vars/volumes,
  weekly rebuilds with PHP patches)
- supabase: bump all 7 components to self-hosted v0.8.3 tags
  (studio, gotrue, postgrest, realtime, storage-api, postgres-meta, kong)

moodle/versions/4/deployment.yaml

@@ -23,7 +23,7 @@ spec:
           type: RuntimeDefault
       containers:
         - name: moodle
-          image: bitnamilegacy/moodle:4.5.2
+          image: oksigenia/moodle:4.5
           ports:
             - name: http
               containerPort: 8080