add SEO enhancements: OG images, meta robots, FAQ block, image sitemap

- Per-page SEO controls: meta robots directives, focus keyword, OG image
- Site-wide default OG image in admin settings
- FAQ block type with FAQPage JSON-LD schema
- Enhanced Organization JSON-LD with business info, contact, address
- Image sitemap with product images
- SEO preview panel with Google/social card mockups
- SEO checklist with real-time scoring
- Business info section in site editor
- GSC integration scaffolding (OAuth, client, cache)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/berrypod_web/controllers/gsc_auth_controller.ex

@@ -0,0 +1,67 @@
+defmodule BerrypodWeb.GSCAuthController do
+  @moduledoc """
+  Handles Google Search Console OAuth flow.
+  """
+
+  use BerrypodWeb, :controller
+
+  alias Berrypod.GSC.{Cache, OAuth}
+
+  @doc """
+  Initiates the OAuth flow by redirecting to Google's consent screen.
+  """
+  def connect(conn, _params) do
+    case OAuth.authorize_url() do
+      {:ok, url} ->
+        redirect(conn, external: url)
+
+      {:error, :missing_client_id} ->
+        conn
+        |> put_flash(
+          :error,
+          "Google Search Console is not configured. Set GSC_CLIENT_ID and GSC_CLIENT_SECRET environment variables."
+        )
+        |> redirect(to: ~p"/admin/gsc")
+    end
+  end
+
+  @doc """
+  Handles the OAuth callback from Google.
+
+  Exchanges the authorization code for tokens and redirects to the dashboard.
+  """
+  def callback(conn, %{"code" => code}) do
+    case OAuth.exchange_code(code) do
+      {:ok, _access_token} ->
+        # Invalidate any stale cache when reconnecting
+        Cache.invalidate()
+
+        conn
+        |> put_flash(:info, "Connected to Google Search Console")
+        |> redirect(to: ~p"/admin/gsc")
+
+      {:error, reason} ->
+        conn
+        |> put_flash(:error, "Failed to connect: #{inspect(reason)}")
+        |> redirect(to: ~p"/admin/gsc")
+    end
+  end
+
+  def callback(conn, %{"error" => error}) do
+    conn
+    |> put_flash(:error, "Authorization denied: #{error}")
+    |> redirect(to: ~p"/admin/gsc")
+  end
+
+  @doc """
+  Disconnects from Google Search Console by clearing stored tokens.
+  """
+  def disconnect(conn, _params) do
+    OAuth.disconnect()
+    Cache.invalidate()
+
+    conn
+    |> put_flash(:info, "Disconnected from Google Search Console")
+    |> redirect(to: ~p"/admin/gsc")
+  end
+end