Encrypt uploads in the browser and send them in chunks

A 6 GB upload kept a customer waiting long after its progress bar
reached 100%. The server wrote every upload three times: PHP's
temporary file, Livewire's copy of it ("Processing files...") and the
encrypted file ("Create Share Link"), each a full rewrite of a slow
disk. The unencrypted copy also stayed behind in livewire-tmp.

Now the uploader's browser encrypts each file in 16 MB chunks with
WebCrypto and PUTs them one at a time; the server checks each chunk in
memory and writes it once, already encrypted. Creating the share only
wraps its key and saves the options. A 200 MB upload through the
Docker image took 2.8 s, and its download matched byte for byte.

- SEALCHK2: a 19-byte header (chunk size, 7-byte nonce prefix), then
  ciphertext and tag per chunk. Each nonce holds the chunk index and a
  last-chunk flag (the STREAM construction), so cut or reordered files
  fail to decrypt. SEALCHK1 and the single-block format still read.
- Envelope encryption: one random key per share. With a password it is
  wrapped with Argon2id (sodium, libsodium's interactive limits) in
  shares.wrapped_key, which names its parameters. Password shares from
  before keep their PBKDF2-derived key.
- The upload page registers each selection with FileUploader into a
  pending share of its own, lists the files with their progress, retries
  a failed chunk after 1-16 s, then offers Retry; Remove and Cancel
  abort. UploadChunkController only accepts chunks from the session that
  started the share: a repeat is acknowledged, a skip gets 409 with the
  count stored. Chunks go out as Blobs, which Chromium sends about eight
  times faster than ArrayBuffers.
- Uploads need a secure context: over plain HTTP the page says HTTPS is
  needed and takes no files. The Docker image gains AUTO_HTTPS, which
  serves Let's Encrypt on 443 for SERVER_NAME and redirects 80; without
  it the container stays on HTTP 80 behind a proxy. docker/Caddyfile was
  never loaded and is gone; docker/healthcheck.sh covers both modes.
- "Download all" streams the ZIP with maennchen/zipstream-php (STORE,
  ZIP64) instead of decrypting whole files into memory and writing the
  archive unencrypted to /tmp.
- Pending shares count towards the quota, stay out of the admin
  dashboard and 404 everywhere else. shares:cleanup deletes uploads idle
  for 4 hours and Livewire temporary files older than that.
- PHP's upload limits no longer cap the admin's max file size and
  default to 64M; LIVEWIRE_MAX_UPLOAD_TIME is gone and
  UPLOAD_CHUNK_SIZE_MB is new.
- Tests cover the format, key wrapping, registration limits, the chunk
  endpoint's answers, completing a share, the streamed ZIP, cleanup,
  and in Chromium a real chunked upload and the HTTPS warning; the
  selected-files overflow test runs again. README, website, CHANGELOG
  and .ai/rules follow.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/Feature/CleanupExpiredSharesTest.php

@@ -2,6 +2,7 @@
 
 use App\Models\Share;
 use Illuminate\Support\Facades\Storage;
+use Livewire\Features\SupportFileUploads\FileUploadConfiguration;
 
 test('cleanup removes expired shares', function () {
     Storage::fake('shares');
@@ -58,3 +59,35 @@ test('cleanup removes both expired and download-limited shares', function () {
     expect(Share::query()->find($limitReached->id))->toBeNull();
     expect(Share::query()->find($active->id))->not->toBeNull();
 });
+
+test('cleanup removes uploads no chunk reached for 4 hours, and keeps recent ones and completed shares', function () {
+    Storage::fake('shares');
+    $this->freezeTime();
+    $abandoned = Share::factory()->pending()->create(['updated_at' => now()->subHours(4)->subMinute()]);
+    Storage::disk('shares')->put($abandoned->token.'/file.enc', 'encrypted');
+    $recent = Share::factory()->pending()->create(['updated_at' => now()->subHours(3)]);
+    $completed = Share::factory()->create(['updated_at' => now()->subDays(3)]);
+
+    $this->artisan('shares:cleanup')
+        ->expectsOutputToContain('Cleaned up 1 abandoned upload(s)')
+        ->assertExitCode(0);
+
+    $this->assertModelMissing($abandoned);
+    $this->assertModelExists($recent);
+    $this->assertModelExists($completed);
+    expect(Storage::disk('shares')->directories())->not->toContain($abandoned->token);
+});
+
+test('cleanup removes temporary upload files older than 4 hours and keeps newer ones', function () {
+    $storage = FileUploadConfiguration::storage();
+    $storage->put(FileUploadConfiguration::path('old.pdf'), 'unencrypted leftover');
+    $storage->put(FileUploadConfiguration::path('new.png'), 'a logo being chosen');
+    touch($storage->path(FileUploadConfiguration::path('old.pdf')), now()->subHours(5)->getTimestamp());
+
+    $this->artisan('shares:cleanup')
+        ->expectsOutputToContain('Cleaned up 1 temporary upload file(s)')
+        ->assertExitCode(0);
+
+    expect($storage->exists(FileUploadConfiguration::path('old.pdf')))->toBeFalse();
+    expect($storage->exists(FileUploadConfiguration::path('new.png')))->toBeTrue();
+});