Fix uploads over 4 GB failing with a misleading size error

Livewire's temporary upload rule was hard-coded to max:4194304 (4 GB),
so /livewire/upload-file rejected any larger file no matter how high
PHP_UPLOAD_MAX_FILESIZE or the admin's max file size were set.
_uploadErrored() then replaced Livewire's actual message with "file
exceeds the maximum size of N MB", quoting the admin limit the file was
under.

The cap is removed: PHP's upload_max_filesize is the hard limit and the
admin setting is still enforced in updatedFiles() and createShare(). A
rejected upload now logs the real validation errors and tells the user
the server could not accept the file.

max_upload_time is configurable via LIVEWIRE_MAX_UPLOAD_TIME, and the
README documents every limit large uploads depend on.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017XYnWFt9pJEwvAmNFN38XD

tests/Feature/FileUploadTest.php

@@ -5,6 +5,7 @@ use App\Livewire\SystemPasswordPrompt;
 use App\Models\Setting;
 use App\Models\Share;
 use Illuminate\Http\UploadedFile;
+use Illuminate\Support\Facades\Log;
 use Illuminate\Support\Facades\Storage;
 use Livewire\Livewire;
 
@@ -119,6 +120,39 @@ test('files added in multiple batches end up in the same share', function () {
     expect($share->files->pluck('original_name')->all())->toBe(['first.txt', 'second.txt']);
 });
 
+test('files larger than 4 GB can be shared when within the admin file size limit', function () {
+    Storage::fake('shares');
+    Setting::set('max_file_size', 15000 * 1024 * 1024);
+    Setting::set('max_size_per_share', 20 * 1024 * 1024 * 1024);
+
+    Livewire::test(FileUploader::class)
+        ->set('files', [UploadedFile::fake()->create('backup.dump', 6 * 1024 * 1024)])
+        ->assertHasNoErrors('files')
+        ->call('createShare')
+        ->assertHasNoErrors()
+        ->assertRedirectContains('/share/');
+
+    expect(Share::query()->first()->total_size)->toBe(6 * 1024 * 1024 * 1024);
+});
+
+test('a rejected upload logs the real reason instead of blaming the file size limit', function () {
+    Log::spy();
+    Setting::set('max_file_size', 15000 * 1024 * 1024);
+
+    $errors = ['files.0' => ['The files.0 failed to upload.']];
+
+    $component = Livewire::test(FileUploader::class)
+        ->call('_uploadErrored', 'files', json_encode(['errors' => $errors]), true)
+        ->assertDispatched('upload:errored');
+
+    expect($component->errors()->first('files'))
+        ->toBe('Upload failed: the server could not accept the file. Please try again or contact the administrator.');
+
+    Log::shouldHaveReceived('warning')
+        ->withArgs(fn (string $message, array $context): bool => $context['errors'] === $errors)
+        ->once();
+});
+
 test('file upload requires at least one file', function () {
     Livewire::test(FileUploader::class)
         ->set('files', [])