Round out DO sync workers: volumes, snapshots, floating IPs, firewalls, LBs

Five new Oban workers, all on cloud_sync_full following the established
droplet/domains pattern (list → normalize → upsert → mark_stale):

- VolumesWorker         — block storage
- SnapshotsWorker       — both droplet and volume snapshots (kind="snapshot"
                          with attrs.resource_type to differentiate)
- FloatingIpsWorker     — provider_id is the IP; status assigned/unassigned
- FirewallsWorker       — inbound/outbound rules + droplet_ids in attrs
- LoadBalancersWorker   — name + region + algorithm + forwarding rules

DigitalOcean.Client gains list_snapshots / list_firewalls / list_load_balancers.

ProjectsWorker URN normalization extended: "floatingip" → floating_ip,
"loadbalancer" → load_balancer, "dbaas" → managed_db. URNs DO emits don't
have underscores for these.

Cron updated: new workers run every 15min on cloud_sync_full; snapshots
moved to hourly (at :33) since they change slowly and listing them is
the most-paginated call we make.

InvoiceIngestWorker.derive_kind/2 reordered to check specific phrases
before generic products — "Droplet Snapshots"/"Droplet Backups" no longer
get bucketed as kind=droplet ahead of the actual snapshot check. Also
adds kind="droplet_backup" for DO's automated backup billing (separate
from the snapshot kind because backups aren't exposed via /v2/snapshots).

Live verified: 12 snapshots discovered + 1 firewall (account has no
volumes / floating IPs / LBs at the moment, so those workers ran clean).
April 2026 invoice match rate jumped from 18.2% → 51.5%. Of the
unmatched: 10 historic droplets that no longer exist on DO, 2 backups
(separate API surface), 1 Spaces bucket (S3 API, deferred), 1 GST
(correctly no kind). Effectively ~95% of currently-extant resources match.

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

lib/arcadia_cloud/sync/snapshots_worker.ex

@@ -0,0 +1,56 @@
+defmodule ArcadiaCloud.Sync.SnapshotsWorker do
+  @moduledoc """
+  Full sync of DO snapshots — both droplet snapshots and volume snapshots.
+  DO returns them together with a `resource_type` field that we use to
+  differentiate; both land as kind="snapshot" with `attrs.resource_type`.
+  """
+  use Oban.Worker, queue: :cloud_sync_full, max_attempts: 3
+
+  alias ArcadiaCloud.Cloud
+  alias ArcadiaCloud.DigitalOcean.Client
+
+  @kind "snapshot"
+  @provider "digitalocean"
+
+  @impl Oban.Worker
+  def perform(_job) do
+    now = DateTime.utc_now() |> DateTime.truncate(:second)
+
+    with {:ok, snapshots} <- Client.list_snapshots() do
+      Enum.each(snapshots, fn s ->
+        Cloud.upsert_resource(normalize(s, now))
+      end)
+
+      Cloud.mark_stale(@kind, now)
+      :ok
+    end
+  end
+
+  defp normalize(s, now) do
+    region =
+      case s["regions"] do
+        [first | _] when is_binary(first) -> first
+        _ -> nil
+      end
+
+    %{
+      provider: @provider,
+      provider_id: to_string(s["id"]),
+      kind: @kind,
+      name: s["name"],
+      region: region,
+      status: "active",
+      tags: s["tags"] || [],
+      attrs: %{
+        resource_type: s["resource_type"],
+        resource_id: s["resource_id"],
+        size_gigabytes: s["size_gigabytes"],
+        min_disk_size: s["min_disk_size"],
+        regions: s["regions"],
+        do_created_at: s["created_at"]
+      },
+      first_seen_at: now,
+      last_seen_at: now
+    }
+  end
+end