FIX: make stable diffusion multi site friendly (#265)

Previous to this change image generation did not work on multisite

There was a background thread generating the images and it was
getting site settings from the default site in the cluster

This also removes referer header which is not needed

lib/modules/ai_bot/commands/image_command.rb

@@ -47,13 +47,25 @@ module DiscourseAi::AiBot::Commands
 
       results = nil
 
+      # this ensures multisite safety since background threads
+      # generate the images
+      api_key = SiteSetting.ai_stability_api_key
+      engine = SiteSetting.ai_stability_engine
+      api_url = SiteSetting.ai_stability_api_url
+
       # API is flaky, so try a few times
       3.times do
         begin
           thread =
             Thread.new do
               begin
-                results = DiscourseAi::Inference::StabilityGenerator.perform!(prompt)
+                results =
+                  DiscourseAi::Inference::StabilityGenerator.perform!(
+                    prompt,
+                    engine: engine,
+                    api_key: api_key,
+                    api_url: api_url,
+                  )
               rescue => e
                 Rails.logger.warn("Failed to generate image for prompt #{prompt}: #{e}")
               end
@@ -65,6 +77,8 @@ module DiscourseAi::AiBot::Commands
         end
       end
 
+      return { prompt: prompt, error: "Something went wrong, could not generate image" } if !results
+
       uploads = []
 
       results[:artifacts].each_with_index do |image, i|

lib/shared/inference/stability_generator.rb

@@ -3,12 +3,15 @@
 module ::DiscourseAi
   module Inference
     class StabilityGenerator
-      def self.perform!(prompt, width: nil, height: nil)
+      def self.perform!(prompt, width: nil, height: nil, api_key: nil, engine: nil, api_url: nil)
+        api_key ||= SiteSetting.ai_stability_api_key
+        engine ||= SiteSetting.ai_stability_engine
+        api_url ||= SiteSetting.ai_stability_api_url
+
         headers = {
-          "Referer" => Discourse.base_url,
           "Content-Type" => "application/json",
           "Accept" => "application/json",
-          "Authorization" => "Bearer #{SiteSetting.ai_stability_api_key}",
+          "Authorization" => "Bearer #{api_key}",
         }
 
         sdxl_allowed_dimentions = [
@@ -24,7 +27,7 @@ module ::DiscourseAi
         ]
 
         if (!width && !height)
-          if SiteSetting.ai_stability_engine.include? "xl"
+          if engine.include? "xl"
             width, height = sdxl_allowed_dimentions[0]
           else
             width, height = [512, 512]
@@ -41,11 +44,9 @@ module ::DiscourseAi
           steps: 30,
         }
 
-        base_url = SiteSetting.ai_stability_api_url
-        engine = SiteSetting.ai_stability_engine
         endpoint = "v1/generation/#{engine}/text-to-image"
 
-        response = Faraday.post("#{base_url}/#{endpoint}", payload.to_json, headers)
+        response = Faraday.post("#{api_url}/#{endpoint}", payload.to_json, headers)
 
         if response.status != 200
           Rails.logger.error(