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/UploadChunkTest.php

@@ -1,6 +1,7 @@
 <?php
 
 use App\Models\Setting;
+use App\Models\Share;
 use App\Models\ShareFile;
 use App\Services\ShareService;
 use Illuminate\Support\Facades\Storage;
@@ -31,6 +32,19 @@ test('a chunk for a pending share this session started is stored', function () {
     expect($file->refresh()->uploaded_chunks)->toBe(1);
 });
 
+test('a chunk that takes the stored bytes beyond the storage quota returns 422', function () {
+    Storage::fake('shares');
+    config(['uploads.chunk_size' => 4]);
+    Setting::set('max_storage_quota', 100);
+    $file = app(ShareService::class)->registerFile(null, 'notes.txt', 6, null);
+    Share::factory()->create(['total_size' => 98]);
+
+    $response = putChunk($this, $file, 0, encryptedChunk($file, 'abcd', 0, false), [$file->share->token]);
+
+    $response->assertStatus(422);
+    expect($file->refresh()->uploaded_chunks)->toBe(0);
+});
+
 test('a chunk for a pending share another session started returns 404', function () {
     Storage::fake('shares');
     $file = app(ShareService::class)->registerFile(null, 'notes.txt', 4, null);