Phase 1 continued: ProjectsWorker, DomainsWorker, Oban Cron schedule

ProjectsWorker mirrors DO Projects to cloud_projects table in a two-pass
sweep: upsert projects, then walk each project's resource membership
(list_project_resources) and update cloud_resources.cloud_project_id +
tenant_id. DO URN kinds get normalized via normalize_kind/1 (domain →
dns_zone, space → spaces_bucket) so attribution matches local naming.

DomainsWorker syncs DNS zones (DO Domains). Same upsert chokepoint, same
three-strike stale handling. Zones are global to the account; attribution
happens via ProjectsWorker if a domain is in a DO project, else stays
NULL pending operator classification.

Oban.Plugins.Cron added with 15-minute schedules for ProjectsWorker,
DropletsWorker, DomainsWorker — workers run automatically once a token
is configured. Phase 0/1 cadence; phase 2 moves droplets to cloud_sync_fast
(1-min) for real-time status visibility.

DigitalOcean.Client gains list_domains / list_volumes / list_floating_ips.
Volumes and floating IPs not yet wired to workers; trivial follow-on.

Live smoke test: 5 droplets + 7 DNS zones discovered, all attributed to
their existing DO projects via membership lookup (skyai-internal becomes
the fallback only for genuinely orphan resources).

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

config/config.exs

@@ -48,6 +48,15 @@ config :arcadia_cloud, Oban,
     metering: 2,
     default: 5
   ],
+  plugins: [
+    {Oban.Plugins.Cron,
+     crontab: [
+       # ProjectsWorker first so attribution is fresh before resource syncs
+       {"*/15 * * * *", ArcadiaCloud.Sync.ProjectsWorker},
+       {"*/15 * * * *", ArcadiaCloud.Sync.DropletsWorker},
+       {"*/15 * * * *", ArcadiaCloud.Sync.DomainsWorker}
+     ]}
+  ],
   repo: ArcadiaCloud.Repo
 
 # Import environment specific config. This must remain at the bottom