Fix the security audit's findings

Fixes the nine findings of security audit run 1 on 2.4.1 (T1-T11).

F1: Uploads that are not complete now count only the bytes the server
received, and a chunk that goes above the storage quota gets 422. An
anonymous uploader can no longer fill the quota with declared sizes.

F2: The share password and the admin login have a second limit without
the address (20 attempts per minute per share and per e-mail), because
a forged X-Forwarded-For changes the address.

F3: The system password gate and the admin check now also run on
Livewire updates, so an old uploader snapshot cannot register files.

F4: The session keeps a fingerprint of the system password's hash.
When the admin changes the system password, earlier verifications end.

F5: The page after the upload opens only in the session that created
the share, and only while recipients can still reach the share.

F6: The share password limit counts an attempt before the password is
checked, so parallel attempts cannot pass it.

F7: The system password has the same two limits (5 per address, 20 in
total per minute).

F8: A password change or reset signs the user's other sessions out.

F9: The only admin cannot delete the account, which would open /setup
to every visitor.

The setup wizard also holds the admin password to the password
defaults, and Livewire applies EnsureAdmin to updates.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Feature/PageTemplateTest.php

@@ -26,7 +26,11 @@ test('every page is one page template, one h1 and the same width', function (Clo
 })->with([
     'upload' => [fn (TestCase $test): TestResponse => $test->get(route('upload'))],
     'download' => [fn (TestCase $test): TestResponse => $test->get(route('share.download', Share::factory()->withPassword()->create()))],
-    'share created' => [fn (TestCase $test): TestResponse => $test->get(route('share.created', Share::factory()->create()))],
+    'share created' => [function (TestCase $test): TestResponse {
+        $share = Share::factory()->create();
+
+        return $test->withSession(['created_shares' => [$share->token]])->get(route('share.created', $share));
+    }],
     'login' => [fn (TestCase $test): TestResponse => $test->get(route('login'))],
     'forgot password' => [fn (TestCase $test): TestResponse => $test->get(route('password.request'))],
     'reset password' => [fn (TestCase $test): TestResponse => $test->get(route('password.reset', 'token'))],