Wire skyai-finance push: cloud invoices flow into Sky AI's books

After InvoiceIngestWorker writes cost lines and matches resources, it
pushes a normalized invoice payload to skyai-finance-svc's new endpoint
POST /api/v1/integrations/cloud/import-invoice. Idempotent — finance
dedups on (tenant_id, source, external_id), so re-runs return "updated"
not duplicate rows.

ArcadiaCloud.Integrations.SkyaiFinance is the HTTP client. Auth is a
short-lived JWT minted via Guardian (shared secret per memory) with
identity {tenant_id: "platform-admin", roles: ["admin"]} — the role
satisfies finance's RequireWriteRole plug. Identity + base URL are
configurable; SKYAI_FINANCE_URL env var can override the default
http://localhost:4010 for arcadia-dev / prod.

GST line detection: lines whose description contains "gst" or "tax"
get summed into amount_tax_minor; everything else into amount_net_minor;
sum stays gross. Phase 1 enough — proper tax handling lands when
real per-tenant invoices flow.

cloud_invoices gains pushed_to_finance_at + finance_invoice_id so we
don't re-push uselessly (Billing.mark_invoice_pushed/2 records both).
A missing finance config (no :skyai_finance app env) makes the push a
silent skip rather than a worker failure — environments without finance
configured still get a working ingest.

Live verified end-to-end against both services:
- April 2026 DO invoice (33 lines, $86.92) lands in finance as a row
  with gross=$86.92, tax=$7.90, source=digitalocean, tenant=platform-admin
- DigitalOcean vendor auto-created (category=cloud) under platform-admin
- Re-running the worker returns action: "updated" not "created";
  finance still has exactly 1 row for the invoice

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

lib/arcadia_cloud/integrations/skyai_finance.ex

@@ -0,0 +1,57 @@
+defmodule ArcadiaCloud.Integrations.SkyaiFinance do
+  @moduledoc """
+  HTTP client for pushing cloud invoices to skyai-finance-svc.
+
+  Auth: mints a short-lived Guardian JWT (shared secret per
+  project_arcadia_guardian_secret memory) with the platform-admin identity
+  configured under `:arcadia_cloud, :skyai_finance`. JWT carries role
+  `admin` because skyai-finance's RequireWriteRole plug accepts `admin`
+  or `user`, not `platform_admin`.
+  """
+
+  alias ArcadiaCloud.Guardian
+
+  @doc """
+  Push a single cloud invoice (and ensure-vendor) to skyai-finance.
+
+  Idempotent — finance dedups on (tenant_id, source, external_id) and
+  updates existing rows on re-push.
+
+  Returns {:ok, %{vendor_id, invoice_id, action}} | {:error, reason}.
+  """
+  def push_invoice(payload) when is_map(payload) do
+    with {:ok, base_url} <- fetch(:base_url),
+         {:ok, identity_claims} <- fetch(:identity_claims),
+         {:ok, token, _claims} <-
+           Guardian.encode_and_sign(identity_claims, identity_claims, token_type: :access) do
+      url = base_url <> "/api/v1/integrations/cloud/import-invoice"
+
+      case Req.post(url,
+             headers: [
+               {"authorization", "Bearer " <> token},
+               {"content-type", "application/json"}
+             ],
+             json: payload,
+             retry: :transient,
+             max_retries: 2,
+             receive_timeout: 15_000
+           ) do
+        {:ok, %Req.Response{status: status, body: body}} when status in 200..299 ->
+          {:ok, body}
+
+        {:ok, %Req.Response{status: status, body: body}} ->
+          {:error, {:http, status, body}}
+
+        {:error, e} ->
+          {:error, {:transport, e}}
+      end
+    end
+  end
+
+  defp fetch(key) do
+    case Application.get_env(:arcadia_cloud, :skyai_finance, [])[key] do
+      nil -> {:error, {:skyai_finance_not_configured, key}}
+      value -> {:ok, value}
+    end
+  end
+end