fix: repair form submission with queued files + add comprehensive debug logging

- Replace fetch(redirect:manual) with XMLHttpRequest in file-upload-queue.js.
  The previous fetch-based redirect detection was broken because opaque
  redirects hide the Location header. XHR's responseURL reliably exposes
  the final URL after server-side redirects.

- Add console.log tracing at every decision point in submit interception:
  entry, hasFiles check, enctype check, double-submit guard, XHR status,
  redirect detection, error fallback.

- Add error_log entry-point logging to all 16 admin action files plus
  the partage/index.php submission handler and password gate. Each logs:
  request method, content type/length, POST keys, file counts, and
  queue-specific file counts where applicable.

- Add double-submit guard (_xamxamActiveSubmit) to prevent duplicate
  XHR sends when the native submit handler fires after interception.

app/templates/partials/form/checkbox-list.php

@@ -16,7 +16,7 @@
  *   string  $hxPost    — optional hx-post URL for HTMX live update
  *   string  $hxTarget  — optional hx-target CSS selector for HTMX swap
  *   string  $hxSwap    — optional hx-swap value; default 'outerHTML'
- *   string  $hxInclude — optional hx-include selector; default 'this, #website-url-fieldset'
+ *   string  $hxInclude — optional hx-include selector; default 'this'
  */
 
 $checked    = $checked    ?? [];
@@ -24,7 +24,7 @@ $required   = $required   ?? false;
 $hxPost     = $hxPost     ?? '';
 $hxTarget   = $hxTarget   ?? '';
 $hxSwap     = $hxSwap     ?? 'outerHTML';
-$hxInclude  = $hxInclude  ?? 'this, #website-url-fieldset';
+$hxInclude  = $hxInclude  ?? 'this';
 ?>
 <div>
     <span class="admin-row-label"><?= htmlspecialchars($label) ?><?= $required ? ' <span class="asterisk">*</span>' : '' ?></span>