Replace hand-rolled auth with Laravel Breeze (Livewire stack)

Adds the auth Breeze scaffolds that were missing before: password
reset and email verification, plus a profile page (update name/email,
change password, delete account). User now implements MustVerifyEmail
so verification is actually enforced, not just scaffolded.

This does mean accepting Tailwind v3 (postcss/tailwind.config.js)
over the v4 CSS-first setup the app started with, and Livewire drops
from ^4.3 to ^3.6.4 — both forced by Breeze/Volt's current
compatibility requirements. Restored the Instrument Sans font Breeze's
installer dropped so styling stays close to what we had.

Reconciliation, since Breeze's installer assumes a blank-slate app:
- Deleted the hand-rolled Login/Register Livewire components/views/
  test — superseded by Breeze's Volt-based auth pages
  (resources/views/livewire/pages/auth/*), which also cover
  forgot-password, reset-password, verify-email, and confirm-password.
- Deleted Breeze's own default welcome/dashboard views and its
  separate app layout + nav component — kept our existing
  components/layouts/app.blade.php as the one real app layout, used
  Breeze's minimal layouts/guest.blade.php only for the auth pages.
- Rewrote routes/web.php merging our routes (home, sites, discover)
  with routes/auth.php; replaced every hardcoded route('dashboard')
  reference (5 Blade files plus, easy to miss, a plain PHP controller
  VerifyEmailController) with sites.index.
- Logout: Breeze's Actions\Logout::__invoke() returns void, so wired
  directly as a route it silently no-ops instead of redirecting;
  fixed with a thin closure that calls it then redirects.
- Fixed Breeze's own generated tests (Auth/AuthenticationTest,
  RegistrationTest, EmailVerificationTest, PasswordConfirmationTest)
  where they assumed the deleted dashboard route/nav component.

Verified: full suite (28 tests, including Breeze's Registration/
Authentication/PasswordReset/PasswordConfirmation/PasswordUpdate/
EmailVerification/Profile tests plus our own GuestPreviewTest) passes
against the huginn_testing MySQL database. Also smoke-tested for real:
all key pages return 200, /profile redirects guests to /login, guest
preview capping still works, and a real password-reset email was
generated and logged with correct branding and a working link.

resources/views/layouts/guest.blade.php

@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<html lang="{{ str_replace('_', '-', app()->getLocale()) }}">
+    <head>
+        <meta charset="utf-8">
+        <meta name="viewport" content="width=device-width, initial-scale=1">
+        <meta name="csrf-token" content="{{ csrf_token() }}">
+
+        <title>{{ config('app.name', 'Laravel') }}</title>
+
+        <!-- Fonts -->
+        <link rel="preconnect" href="https://fonts.bunny.net">
+        <link href="https://fonts.bunny.net/css?family=instrument-sans:400,500,600&display=swap" rel="stylesheet" />
+
+        <!-- Scripts -->
+        @vite(['resources/css/app.css', 'resources/js/app.js'])
+    </head>
+    <body class="font-sans text-gray-900 antialiased">
+        <div class="min-h-screen flex flex-col sm:justify-center items-center pt-6 sm:pt-0 bg-gray-100 dark:bg-gray-900">
+            <div>
+                <a href="/" wire:navigate class="text-2xl font-semibold text-gray-900 dark:text-gray-100">Huginn</a>
+            </div>
+
+            <div class="w-full sm:max-w-md mt-6 px-6 py-4 bg-white dark:bg-gray-800 shadow-md overflow-hidden sm:rounded-lg">
+                {{ $slot }}
+            </div>
+        </div>
+    </body>
+</html>