add admin email settings page with provider selection

Card radio component for picking email providers (SMTP, SendGrid, Mailjet, etc.)
with instant client-side switching via JS hook. Adapter configs are pre-rendered
and toggled without a server round-trip. Secrets are preserved when re-saving
with blank password fields. Includes from address field, test email sending,
and disconnect flow.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/berrypod/mailer/adapters_test.exs

@@ -0,0 +1,78 @@
+defmodule Berrypod.Mailer.AdaptersTest do
+  use ExUnit.Case, async: true
+
+  alias Berrypod.Mailer.Adapters
+
+  describe "all/0" do
+    test "returns a list of adapters" do
+      adapters = Adapters.all()
+      assert is_list(adapters)
+      assert length(adapters) >= 9
+    end
+
+    test "each adapter has required keys" do
+      for adapter <- Adapters.all() do
+        assert is_binary(adapter.key)
+        assert is_binary(adapter.name)
+        assert is_atom(adapter.module)
+        assert is_binary(adapter.description)
+        assert is_list(adapter.fields)
+        assert length(adapter.fields) >= 1
+      end
+    end
+
+    test "each adapter has a url (or nil for SMTP)" do
+      for adapter <- Adapters.all() do
+        if adapter.key == "smtp" do
+          assert is_nil(adapter.url)
+        else
+          assert is_binary(adapter.url)
+        end
+      end
+    end
+
+    test "each field has required keys" do
+      for adapter <- Adapters.all(), field <- adapter.fields do
+        assert is_binary(field.key)
+        assert is_binary(field.label)
+        assert field.type in [:string, :integer, :secret]
+      end
+    end
+  end
+
+  describe "get/1" do
+    test "returns adapter by key" do
+      assert %{key: "smtp", name: "SMTP"} = Adapters.get("smtp")
+      assert %{key: "postmark", name: "Postmark"} = Adapters.get("postmark")
+      assert %{key: "mailjet", name: "Mailjet"} = Adapters.get("mailjet")
+      assert %{key: "mailpace", name: "MailPace"} = Adapters.get("mailpace")
+      assert %{key: "postal", name: "Postal"} = Adapters.get("postal")
+    end
+
+    test "returns nil for unknown key" do
+      assert is_nil(Adapters.get("unknown"))
+    end
+  end
+
+  describe "field_keys/1" do
+    test "returns settings keys prefixed with email_" do
+      smtp = Adapters.get("smtp")
+      keys = Adapters.field_keys(smtp)
+
+      assert "email_relay" in keys
+      assert "email_port" in keys
+      assert "email_username" in keys
+      assert "email_password" in keys
+    end
+  end
+
+  describe "all_field_keys/0" do
+    test "returns unique keys from all adapters" do
+      keys = Adapters.all_field_keys()
+      assert is_list(keys)
+      assert "email_api_key" in keys
+      assert "email_relay" in keys
+      assert length(keys) == length(Enum.uniq(keys))
+    end
+  end
+end

test/berrypod/mailer_test.exs

@@ -0,0 +1,79 @@
+defmodule Berrypod.MailerTest do
+  use Berrypod.DataCase, async: false
+
+  alias Berrypod.Mailer
+  alias Berrypod.Settings
+
+  setup do
+    # Store original config to restore after each test
+    original = Application.get_env(:berrypod, Mailer)
+    on_exit(fn -> Application.put_env(:berrypod, Mailer, original) end)
+    :ok
+  end
+
+  describe "email_configured?/0" do
+    test "returns false with Local adapter" do
+      Application.put_env(:berrypod, Mailer, adapter: Swoosh.Adapters.Local)
+      refute Mailer.email_configured?()
+    end
+
+    test "returns true with a real adapter" do
+      Application.put_env(:berrypod, Mailer, adapter: Swoosh.Adapters.Postmark, api_key: "test")
+      assert Mailer.email_configured?()
+    end
+  end
+
+  describe "load_config/0" do
+    test "loads adapter config from settings" do
+      Settings.put_setting("email_adapter", "postmark")
+      Settings.put_secret("email_api_key", "pm_test_key_123")
+
+      Mailer.load_config()
+
+      config = Application.get_env(:berrypod, Mailer)
+      assert config[:adapter] == Swoosh.Adapters.Postmark
+      assert config[:api_key] == "pm_test_key_123"
+    end
+
+    test "loads SMTP config with multiple fields" do
+      Settings.put_setting("email_adapter", "smtp")
+      Settings.put_setting("email_relay", "smtp.example.com")
+      Settings.put_setting("email_port", 465, "integer")
+      Settings.put_setting("email_username", "user@example.com")
+      Settings.put_secret("email_password", "secret123")
+
+      Mailer.load_config()
+
+      config = Application.get_env(:berrypod, Mailer)
+      assert config[:adapter] == Swoosh.Adapters.SMTP
+      assert config[:relay] == "smtp.example.com"
+      assert config[:port] == 465
+      assert config[:username] == "user@example.com"
+      assert config[:password] == "secret123"
+    end
+
+    test "is a no-op when no email_adapter is set" do
+      original = Application.get_env(:berrypod, Mailer)
+      Mailer.load_config()
+      assert Application.get_env(:berrypod, Mailer) == original
+    end
+  end
+
+  describe "current_config/0" do
+    test "returns {nil, %{}} when no adapter configured" do
+      Application.put_env(:berrypod, Mailer, adapter: Swoosh.Adapters.Local)
+      assert {nil, %{}} = Mailer.current_config()
+    end
+
+    test "returns adapter key and config when configured from settings" do
+      Settings.put_setting("email_adapter", "postmark")
+      Settings.put_secret("email_api_key", "pm_test_key_123")
+
+      Mailer.load_config()
+
+      {adapter_key, config} = Mailer.current_config()
+      assert adapter_key == "postmark"
+      assert config["api_key"] =~ "•••"
+    end
+  end
+end