migrate: replace NextAuth.js with Better Auth

- Install better-auth and @better-auth/drizzle-adapter
- Create src/lib/auth.ts with Better Auth configuration using bcrypt
- Update database schema: change auth table IDs from uuid to text
- Update route handler from /api/auth/[...nextauth] to /api/auth/[...all]
- Update tRPC context and middleware for Better Auth session handling
- Update client components to use Better Auth APIs (signIn, signOut)
- Update seed script with text-based IDs and correct account schema
- Fix type errors in wizard components (robotId, optional chaining)
- Fix API paths: api.robots.initialize -> api.robots.plugins.initialize
- Update auth router to use text IDs for Better Auth compatibility

Note: Auth tables were reset - users will need to re-register.

src/components/dashboard/app-sidebar.tsx

@@ -3,7 +3,7 @@
 import React, { useEffect, useRef } from "react";
 import Link from "next/link";
 import { usePathname } from "next/navigation";
-import { signOut, useSession } from "next-auth/react";
+import { signOut, useSession } from "~/lib/auth-client";
 import { toast } from "sonner";
 import {
   BarChart3,
@@ -203,7 +203,8 @@ export function AppSidebar({
     : [];
 
   const handleSignOut = async () => {
-    await signOut({ callbackUrl: "/" });
+    await signOut();
+    window.location.href = "/";
   };
 
   const handleStudySelect = async (studyId: string) => {