Show the NPC portrait on the detail page

Npc::getPortraitPath() maps the name to image/npc-pictures/<NameNoSpaces>.png;
the edit page renders it beside the heading (with family · occupation), and
drops the <img> via onerror when a portrait is missing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/Entity/Npc.php

@@ -227,4 +227,14 @@ class Npc
     {
         return $this->updatedAt;
     }
+
+    /**
+     * AssetMapper logical path of this NPC's portrait, e.g.
+     * "image/npc-pictures/GarrickVoss.png". The file may not exist for
+     * NPCs added after the portrait sets were generated.
+     */
+    public function getPortraitPath(): string
+    {
+        return 'image/npc-pictures/'.str_replace(' ', '', $this->name).'.png';
+    }
 }