fix production deployment: CSS, images and theme seeding

- Add @source for shop_components/ directory in app-shop.css (Tailwind
  wasn't scanning sub-modules after the refactor, dropping ~73 utilities)
- Remove overly aggressive .dockerignore rules that excluded mockup
  image variants needed by the responsive_image component
- Seed default theme settings on first boot via Release.seed_defaults/0
  in the supervision tree (seeds.exs doesn't run in releases)
- Fix PDP gallery images for mock data by appending -1200.webp to
  bare mockup base paths
- Update fly.toml format from fly launch

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

fly.toml

@@ -1,50 +1,41 @@
-# fly.toml — Fly.io deployment configuration
+# fly.toml app configuration file generated for simpleshop-theme on 2026-02-08T20:51:20Z
+#
+# See https://fly.io/docs/reference/configuration/ for information about how to use this file.
 #
-# Getting started:
-#   1. Install flyctl: curl -L https://fly.io/install.sh | sh
-#   2. Sign up / log in: fly auth login
-#   3. Create the app: fly launch --no-deploy
-#   4. Create a volume: fly volumes create simpleshop_data --size 1
-#   5. Set secrets:
-#        fly secrets set SECRET_KEY_BASE=$(mix phx.gen.secret)
-#        fly secrets set PHX_HOST=your-domain.com
-#   6. Deploy: fly deploy
-#   7. Open: fly open
 
-app = "simpleshop-theme"
-primary_region = "lhr"
+app = 'simpleshop-theme'
+primary_region = 'lhr'
 
 [build]
-  dockerfile = "Dockerfile"
-
-# SQLite needs a persistent volume — without this, your database is lost on every deploy.
-[mounts]
-  source = "simpleshop_data"
-  destination = "/data"
+  dockerfile = 'Dockerfile'
 
 [env]
-  PHX_SERVER = "true"
-  DATABASE_PATH = "/data/simpleshop_theme.db"
+  DATABASE_PATH = '/data/simpleshop_theme.db'
+  PHX_SERVER = 'true'
+
+[[mounts]]
+  source = 'simpleshop_data'
+  destination = '/data'
 
 [http_service]
   internal_port = 4000
   force_https = true
-  auto_stop_machines = "stop"
+  auto_stop_machines = 'stop'
   auto_start_machines = true
   min_machines_running = 0
 
   [http_service.concurrency]
-    type = "connections"
+    type = 'connections'
     hard_limit = 1000
     soft_limit = 1000
 
-[[http_service.checks]]
-  grace_period = "30s"
-  interval = "15s"
-  method = "GET"
-  timeout = "5s"
-  path = "/health"
+  [[http_service.checks]]
+    interval = '15s'
+    timeout = '5s'
+    grace_period = '30s'
+    method = 'GET'
+    path = '/health'
 
 [[vm]]
-  size = "shared-cpu-1x"
-  memory = "1gb"
+  size = 'shared-cpu-1x'
+  memory = '1gb'