Fix: Set consistent fill color for OpenAI/MoonShot/Grok SVG to prevent color inversion in dark mode

app/icons/llm-icons/grok.svg

@@ -1,4 +1,4 @@
-<svg fill="currentColor" fill-rule="evenodd" height="1em" style="flex:none;line-height:1" viewBox="0 0 30 30"
+<svg fill="#333" fill-rule="evenodd" height="1em" style="flex:none;line-height:1" viewBox="0 0 30 30"
      width="1em" xmlns="http://www.w3.org/2000/svg">
     <title>Grok</title>
     <rect width="30" height="30" fill="#E7F8FF" rx="6"/>

app/icons/llm-icons/moonshot.svg

@@ -1,4 +1,4 @@
-<svg fill="currentColor" fill-rule="evenodd" height="1em" style="flex:none;line-height:1" viewBox="0 0 30 30"
+<svg fill="#333" fill-rule="evenodd" height="1em" style="flex:none;line-height:1" viewBox="0 0 30 30"
      width="1em" xmlns="http://www.w3.org/2000/svg">
     <title>MoonshotAI</title>
     <rect width="30" height="30" fill="#E7F8FF" rx="6"/>

app/icons/llm-icons/openai.svg

@@ -1,4 +1,4 @@
-<svg fill="currentColor" fill-rule="evenodd" height="1em" style="flex:none;line-height:1" viewBox="0 0 30 30"
+<svg fill="#333" fill-rule="evenodd" height="1em" style="flex:none;line-height:1" viewBox="0 0 30 30"
      width="1em" xmlns="http://www.w3.org/2000/svg">
     <title>OpenAI</title>
     <rect width="30" height="30" fill="#E7F8FF" rx="6"/>