fix(admin): replicate reference front-submit settings page 1:1

- Rewrite post_list/submit schema (PHP + JS) with the reference theme's
  field set, order, defaults and dependencies; topics fields excluded
- Map PostDisplay::get_submit_settings() and the FrontSubmit runtime to
  the new keys without legacy fallback
- Guest submission follows the capability matrix; category required on
  submit; pay limits read from the cash/points fieldset
- Drop dead front_submit_* settings, template branches and JS config
- Add submit settings reference contract test

templates/parts/submit/sidebar-terms.php

@@ -25,7 +25,6 @@ require_once get_template_directory() . '/templates/parts/submit/term-checks.php
 <div class="zib-widget mb10-sm">
 	<div class="title-theme mb10"><?php esc_html_e('文章参数', 'aksrt'); ?></div>
 	<div class="term-select-box">
-		<?php if (!empty($settings['allow_category'])) : ?>
 		<div class="newpost-cat-drop drop-select dropdown dependency-box">
 			<button type="button" data-toggle-class="open" data-target=".newpost-cat-drop" class="flex ac jsb drop-btn form-control mb6">
 				<span class="title-theme222"><i class="fa fas fa-folder-open mr6" aria-hidden="true"></i><?php esc_html_e('分类', 'aksrt'); ?></span><i class="ml6 fa fas fa-angle-right em12"></i>
@@ -42,7 +41,6 @@ require_once get_template_directory() . '/templates/parts/submit/term-checks.php
 				</div>
 			</div>
 		</div>
-		<?php endif; ?>
 
 		<?php if (!empty($settings['custom_filter_s']) && !empty($ctx['custom_dimensions'])) : ?>
 			<?php foreach ($ctx['custom_dimensions'] as $dimension) :