feat: wire shop LiveViews to real product data

PreviewData now queries the Products context when real products exist,
falling back to mock data otherwise. Shop pages automatically display
synced Printify products.

Fixes:
- Printify image position was string ("front"), now uses index
- Category extraction improved to match more Printify tags
- ProductShow finds products by slug for real data

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

lib/simpleshop_theme/providers/printify.ex

@@ -200,10 +200,12 @@ defmodule SimpleshopTheme.Providers.Printify do
     images
     |> Enum.with_index()
     |> Enum.map(fn {img, index} ->
+      # Printify returns position as a label string (e.g., "front", "back")
+      # We use the index as the numeric position instead
       %{
         src: img["src"],
-        position: img["position"] || index,
-        alt: nil
+        position: index,
+        alt: img["position"]
       }
     end)
   end
@@ -243,18 +245,27 @@ defmodule SimpleshopTheme.Providers.Printify do
   end
 
   defp extract_category(raw) do
-    # Try to extract category from tags
-    tags = raw["tags"] || []
+    # Try to extract category from tags (case-insensitive)
+    tags =
+      (raw["tags"] || [])
+      |> Enum.map(&String.downcase/1)
 
     cond do
-      "apparel" in tags or "clothing" in tags -> "Apparel"
-      "homeware" in tags or "home" in tags -> "Homewares"
-      "accessories" in tags -> "Accessories"
-      "art" in tags or "print" in tags -> "Art Prints"
-      true -> nil
+      has_tag?(tags, ~w[t-shirt tshirt shirt hoodie sweatshirt apparel clothing]) -> "Apparel"
+      has_tag?(tags, ~w[mug cup blanket pillow cushion homeware homewares home]) -> "Homewares"
+      has_tag?(tags, ~w[notebook journal stationery]) -> "Stationery"
+      has_tag?(tags, ~w[phone case bag tote accessories]) -> "Accessories"
+      has_tag?(tags, ~w[art print poster canvas wall]) -> "Art Prints"
+      true -> List.first(raw["tags"])
     end
   end
 
+  defp has_tag?(tags, keywords) do
+    Enum.any?(tags, fn tag ->
+      Enum.any?(keywords, fn keyword -> String.contains?(tag, keyword) end)
+    end)
+  end
+
   defp normalize_order_status(raw) do
     %{
       status: map_order_status(raw["status"]),