Add admin panel web UI (Svelte 5)

Dashboard with launch stats, instance manager with Modrinth/CurseForge
search and zip import, player and group management, launcher design
editor with live preview, and sign-in settings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011ARcGWxLx21FwXJ3yfGriS

panel/web/index.html

@@ -0,0 +1,14 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <meta name="color-scheme" content="dark" />
+    <link rel="icon" href="/favicon.svg" type="image/svg+xml" />
+    <title>ScopeNet Panel</title>
+  </head>
+  <body>
+    <div id="app"></div>
+    <script type="module" src="/src/main.ts"></script>
+  </body>
+</html>