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/Admin/AdminDashboardTest.php

@@ -151,7 +151,7 @@ test('the shares list excludes the private text from its file count and shows it
         ->assertDontSee('3 files');
 });
 
-test('shares whose files are still uploading are neither listed nor counted, but their bytes count as used space', function () {
+test('shares whose files are still uploading are neither listed nor counted, but only their received bytes count as used space', function () {
     $admin = User::query()->where('is_admin', true)->first();
     $completed = Share::factory()->create(['token' => 'completedshare01', 'total_size' => 1000]);
     ShareFile::factory()->for($completed)->create();
@@ -165,5 +165,5 @@ test('shares whose files are still uploading are neither listed nor counted, but
         ->assertViewHas('totalShares', 1)
         ->assertViewHas('activeShares', 1)
         ->assertViewHas('totalFiles', 1)
-        ->assertViewHas('usedSpace', 1500);
+        ->assertViewHas('usedSpace', 1000);
 });