Fix redirect loop after admin setup by invalidating setup cache

The setupCheckHandle hook caches whether setup is needed for 1 minute.
After creating the admin, this cache wasn't cleared, causing a redirect
loop between /login and /setup.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/hooks.server.ts

@@ -11,6 +11,14 @@ import { supabaseAdmin } from '$lib/server/supabase';
 let setupCheckCache: { needsSetup: boolean; checkedAt: number } | null = null;
 const SETUP_CACHE_TTL = 60000; // 1 minute cache
 
+/**
+ * Invalidate the setup check cache
+ * Call this after creating the first admin user
+ */
+export function invalidateSetupCache() {
+	setupCheckCache = null;
+}
+
 /**
  * Supabase authentication hook
  * Sets up the Supabase client with cookie handling for SSR

src/routes/setup/+page.server.ts

@@ -2,6 +2,7 @@ import { fail, redirect } from '@sveltejs/kit';
 import type { Actions, PageServerLoad } from './$types';
 import { supabaseAdmin } from '$lib/server/supabase';
 import { sendEmail, wrapInMonacoTemplate } from '$lib/server/email';
+import { invalidateSetupCache } from '../../hooks.server';
 
 export const load: PageServerLoad = async () => {
 	// Check if any users exist in the system
@@ -249,6 +250,9 @@ export const actions: Actions = {
 			// Non-critical - continue anyway since the account was created successfully
 		}
 
+		// Clear the setup cache so other routes don't redirect back to /setup
+		invalidateSetupCache();
+
 		// Success - redirect to login
 		throw redirect(303, '/login?setup=complete');
 	}