Phase 0 scaffold: arcadia-cloud Phoenix service

API-only Phoenix 1.8 project for cloud-ops, inventory, billing, and
provisioning sagas. Validates arcadia JWTs via shared Guardian secret
(verify-only; arcadia-app remains the issuer).

Deps beyond default Phoenix: guardian, cors_plug, oban, req.
Postgres on local port 5433 per arcadia stack convention.
Endpoint runs on :4005.

Endpoints:
- GET /api/health         — public, returns service identifier
- GET /api/v1/inventory   — auth-gated, returns empty list (phase 0 stub)

Oban configured with the queues phase 1+ will need:
provisioning / cloud_sync_fast|full|slow / cloud_billing / metering.

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

mix.exs

@@ -0,0 +1,74 @@
+defmodule ArcadiaCloud.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :arcadia_cloud,
+      version: "0.1.0",
+      elixir: "~> 1.15",
+      elixirc_paths: elixirc_paths(Mix.env()),
+      start_permanent: Mix.env() == :prod,
+      aliases: aliases(),
+      deps: deps(),
+      listeners: [Phoenix.CodeReloader]
+    ]
+  end
+
+  # Configuration for the OTP application.
+  #
+  # Type `mix help compile.app` for more information.
+  def application do
+    [
+      mod: {ArcadiaCloud.Application, []},
+      extra_applications: [:logger, :runtime_tools]
+    ]
+  end
+
+  def cli do
+    [
+      preferred_envs: [precommit: :test]
+    ]
+  end
+
+  # Specifies which paths to compile per environment.
+  defp elixirc_paths(:test), do: ["lib", "test/support"]
+  defp elixirc_paths(_), do: ["lib"]
+
+  # Specifies your project dependencies.
+  #
+  # Type `mix help deps` for examples and options.
+  defp deps do
+    [
+      {:phoenix, "~> 1.8.7"},
+      {:phoenix_ecto, "~> 4.5"},
+      {:ecto_sql, "~> 3.13"},
+      {:postgrex, ">= 0.0.0"},
+      {:telemetry_metrics, "~> 1.0"},
+      {:telemetry_poller, "~> 1.0"},
+      {:gettext, "~> 1.0"},
+      {:jason, "~> 1.2"},
+      {:dns_cluster, "~> 0.2.0"},
+      {:bandit, "~> 1.5"},
+      {:guardian, "~> 2.3"},
+      {:cors_plug, "~> 3.0"},
+      {:oban, "~> 2.18"},
+      {:req, "~> 0.5"}
+    ]
+  end
+
+  # Aliases are shortcuts or tasks specific to the current project.
+  # For example, to install project dependencies and perform other setup tasks, run:
+  #
+  #     $ mix setup
+  #
+  # See the documentation for `Mix` for more info on aliases.
+  defp aliases do
+    [
+      setup: ["deps.get", "ecto.setup"],
+      "ecto.setup": ["ecto.create", "ecto.migrate", "run priv/repo/seeds.exs"],
+      "ecto.reset": ["ecto.drop", "ecto.setup"],
+      test: ["ecto.create --quiet", "ecto.migrate --quiet", "test"],
+      precommit: ["compile --warnings-as-errors", "deps.unlock --unused", "format", "test"]
+    ]
+  end
+end