Add attribution and GitHub link to help tooltip

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: keyhell

src/components/replica-builder/settings/UsageHelpContent.tsx

@@ -19,6 +19,22 @@ export function UsageHelpContent() {
   return (
     <div className="grid grid-cols-7 gap-x-2 gap-y-3 py-2 text-xs">
       <div className="col-span-full">
+        <p className="mt-0 mb-3">
+          This application was originally developed by the{' '}
+          <a href="https://nextfusion.org/" target="_blank" rel="noreferrer" className="underline">
+            Next Step Fusion
+          </a>{' '}
+          team. The source code is available on{' '}
+          <a
+            href="https://github.com/Next-Step-Fusion/replica-builder"
+            target="_blank"
+            rel="noreferrer"
+            className="underline"
+          >
+            GitHub
+          </a>
+          .
+        </p>
         <h3 className="mt-0 mb-2 text-sm font-bold">Units</h3>
         <div>
           Coordinates and dimensions - <b>millimeters</b>. Angles - <b>degrees</b>.