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  test — superseded by Breeze's Volt-based auth pages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.

routes/auth.php

@@ -0,0 +1,31 @@
+<?php
+
+use App\Http\Controllers\Auth\VerifyEmailController;
+use Illuminate\Support\Facades\Route;
+use Livewire\Volt\Volt;
+
+Route::middleware('guest')->group(function () {
+    Volt::route('register', 'pages.auth.register')
+        ->name('register');
+
+    Volt::route('login', 'pages.auth.login')
+        ->name('login');
+
+    Volt::route('forgot-password', 'pages.auth.forgot-password')
+        ->name('password.request');
+
+    Volt::route('reset-password/{token}', 'pages.auth.reset-password')
+        ->name('password.reset');
+});
+
+Route::middleware('auth')->group(function () {
+    Volt::route('verify-email', 'pages.auth.verify-email')
+        ->name('verification.notice');
+
+    Route::get('verify-email/{id}/{hash}', VerifyEmailController::class)
+        ->middleware(['signed', 'throttle:6,1'])
+        ->name('verification.verify');
+
+    Volt::route('confirm-password', 'pages.auth.confirm-password')
+        ->name('password.confirm');
+});