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/Browser/ShareFlowTest.php

@@ -45,12 +45,37 @@ test('tab reaches Browse Files with its focus ring, and Enter or Space opens the
 });
 
 test('the selected files list avoids horizontal overflow once files are chosen', function () {
-    // Pest's in-process browser server never parses the multipart body a real file selection sends
-    // (vendor/pestphp/pest-plugin-browser/src/Drivers/LaravelHttpServer.php:257, `[], // @TODO
-    // files...`) — Livewire's temporary-upload request has nowhere to land, so a selected file can
-    // never reach this list to be measured. tests/Feature/FileUploadTest.php covers the list's data
-    // through Livewire::test(); driving a real selection through the browser is impractical here.
-})->skip('the in-process browser server drops multipart uploads (LaravelHttpServer.php:257): a real file selection cannot reach the list');
+    $path = sys_get_temp_dir().'/a-genuinely-quite-long-holiday-photos-archive-from-portugal-'.uniqid().'.zip';
+    file_put_contents($path, 'archive');
+
+    $page = ready(visit('/upload')->resize(393, 852));
+    $page->attach('[data-test="file-input"]', $path)
+        ->waitForText('Uploaded');
+
+    $rows = $page->script("(() => {
+        const rows = [...document.querySelectorAll('[data-test=selected-file]')];
+        return { count: rows.length, allFit: rows.every((row) => row.getBoundingClientRect().right <= window.innerWidth + 0.5) };
+    })()");
+
+    expect($rows['count'])->toBe(1);
+    expect($rows['allFit'])->toBeTrue();
+    $page->assertScript('document.documentElement.scrollWidth <= window.innerWidth')
+        ->assertNoJavaScriptErrors();
+
+    unlink($path);
+});
+
+test('without a secure context the upload page says HTTPS is needed and takes no files', function () {
+    $page = ready(visit('/upload'));
+
+    $page->script("window.eval(\"Alpine.\$data(document.querySelector('[data-test=drop-zone]')).secure = false\")");
+
+    $page->assertScript("getComputedStyle(document.querySelector('[data-test=insecure-context]')).display !== 'none'")
+        ->assertSee('Uploads need a secure connection (HTTPS).')
+        ->assertScript("document.querySelector('[data-test=file-input]').disabled === true")
+        ->assertScript("document.querySelector('[data-test=drop-zone]').getAttribute('aria-disabled') === 'true'")
+        ->assertNoJavaScriptErrors();
+});
 
 test('the drop zone hides its burst again once the drag leaves', function () {
     $page = ready(visit('/upload'));