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/router.ex

@@ -152,6 +152,11 @@ defmodule BerrypodWeb.Router do
     post "/providers", ProvidersController, :create
     post "/providers/:id", ProvidersController, :update
 
+    # GSC OAuth routes
+    get "/gsc/connect", GSCAuthController, :connect
+    get "/gsc/callback", GSCAuthController, :callback
+    delete "/gsc/disconnect", GSCAuthController, :disconnect
+
     live_session :admin,
       layout: {BerrypodWeb.Layouts, :admin},
       on_mount: [
@@ -182,6 +187,7 @@ defmodule BerrypodWeb.Router do
       live "/newsletter/campaigns/new", Admin.Newsletter.CampaignForm, :new
       live "/newsletter/campaigns/:id", Admin.Newsletter.CampaignForm, :edit
       live "/redirects", Admin.Redirects, :index
+      live "/gsc", Admin.GSC, :index
     end
 
     # Theme editor redirects to on-site editing