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/server/api/trpc.ts

@@ -12,7 +12,8 @@ import superjson from "superjson";
 import { ZodError } from "zod";
 
 import { and, eq } from "drizzle-orm";
-import { auth } from "~/server/auth";
+import { headers } from "next/headers";
+import { auth } from "~/lib/auth";
 import { db } from "~/server/db";
 import { userSystemRoles } from "~/server/db/schema";
 
@@ -29,7 +30,9 @@ import { userSystemRoles } from "~/server/db/schema";
  * @see https://trpc.io/docs/server/context
  */
 export const createTRPCContext = async (opts: { headers: Headers }) => {
-  const session = await auth();
+  const session = await auth.api.getSession({
+    headers: await headers(),
+  });
 
   return {
     db,