Abstract AI image provider configuration

public/web.config

@@ -40,6 +40,15 @@
     <!-- Cache-bust parameter name (default: "v") -->
     <add key="CacheBustParamName" value="v" />
 
+    <!-- Image generation provider (pollinations / abacus) -->
+    <add key="AiImageProvider" value="pollinations" />
+
+    <!-- Base URL for image generation when using the current provider -->
+    <add key="AiImageBaseUrl" value="https://image.pollinations.ai/prompt/" />
+
+    <!-- Optional Abacus image endpoint override if Abacus is ever enabled for images -->
+    <add key="AbacusImageBaseUrl" value="" />
+
     <!-- Abacus RouteLLM endpoint for AI-generated post content -->
     <add key="AbacusApiBaseUrl" value="https://routellm.abacus.ai/v1" />