feat(KB-244): add GitHub logo icon for import button

- Add custom GitHubLogo SVG component with Octocat mark
- Replace Download icon with GitHubLogo in desktop import button
- Replace Download icon with GitHubLogo in mobile overflow menu
- Use currentColor for automatic light/dark theme compatibility

packages/dashboard/app/components/Header.tsx

@@ -1,5 +1,20 @@
 import { useState, useEffect, useRef, useCallback } from "react";
-import { Settings, Pause, Play, Square, Download, LayoutGrid, List, Terminal, Lightbulb, Search, X, Activity, MoreHorizontal, Clock, Folder, History } from "lucide-react";
+import { Settings, Pause, Play, Square, LayoutGrid, List, Terminal, Lightbulb, Search, X, Activity, MoreHorizontal, Clock, Folder, History } from "lucide-react";
+
+// GitHub logo icon (Octocat mark) - uses currentColor for theme compatibility
+function GitHubLogo({ size = 16 }: { size?: number }) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      fill="currentColor"
+      aria-hidden="true"
+    >
+      <path d="M12 2C6.477 2 2 6.484 2 12.017c0 4.425 2.865 8.18 6.839 9.504.5.092.682-.217.682-.483 0-.237-.008-.868-.013-1.703-2.782.605-3.369-1.343-3.369-1.343-.454-1.158-1.11-1.466-1.11-1.466-.908-.62.069-.608.069-.608 1.003.07 1.531 1.032 1.531 1.032.892 1.53 2.341 1.088 2.91.832.092-.647.35-1.088.636-1.338-2.22-.253-4.555-1.113-4.555-4.951 0-1.093.39-1.988 1.029-2.688-.103-.253-.446-1.272.098-2.65 0 0 .84-.27 2.75 1.026A9.564 9.564 0 0112 6.844c.85.004 1.705.115 2.504.337 1.909-1.296 2.747-1.027 2.747-1.027.546 1.379.203 2.398.1 2.651.64.7 1.028 1.595 1.028 2.688 0 3.848-2.339 4.695-4.566 4.942.359.309.678.92.678 1.855 0 1.338-.012 2.419-.012 2.747 0 .268.18.58.688.482A10.019 10.019 0 0022 12.017C22 6.484 17.522 2 12 2z" />
+    </svg>
+  );
+}
 
 interface HeaderProps {
   onOpenSettings?: () => void;
@@ -236,7 +251,7 @@ export function Header({
         {/* Desktop actions */}
         {!isMobile && (
           <button className="btn-icon" onClick={onOpenGitHubImport} title="Import from GitHub">
-            <Download size={16} />
+            <GitHubLogo size={16} />
           </button>
         )}
 
@@ -363,7 +378,7 @@ export function Header({
               onClick={() => handleOverflowAction(onOpenGitHubImport)}
               role="menuitem"
             >
-              <Download size={16} />
+              <GitHubLogo size={16} />
               <span>Import from GitHub</span>
             </button>
             <button