feat(pay): show 点击复制{copy name} tooltip on the remark button

Hovering the remark gave no affordance hint that it copies anything. The
reference theme titles the same button 点击复制{copy name} and omits the
tooltip entirely when no copy name is configured.

Emit data-toggle="tooltip" with that title on both copy buttons, gated on a
non-empty copy name, and mirror it on the paid-card helper so the two
surfaces agree. Bootstrap's tooltip init already runs in auto_fun() on load,
which is where the clipboard lib is required too.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/parts/resource-download-box.php

@@ -390,6 +390,7 @@ if ($is_need_purchase && $user_amount > 0) {
 								</a>
 								<?php if ($has_extract || $has_copy) : ?>
 									<button type="button" class="resource-download-box__btn resource-download-box__btn--extract"
+										<?php if ($has_copy && $copy_key !== '') : ?>data-toggle="tooltip" title="<?php echo esc_attr(sprintf(__('点击复制%s', 'aksrt'), $copy_key)); ?>"<?php endif; ?>
 										data-clipboard-tag="<?php echo esc_attr($has_copy ? ($copy_key !== '' ? $copy_key : __('内容', 'aksrt')) : __('提取码', 'aksrt')); ?>"
 										data-clipboard-text="<?php echo esc_attr($has_copy ? $copy_val : $extract_code); ?>"
 									><?php echo esc_html($has_extract ? $extract_code : ($copy_key !== '' ? $copy_key : __('复制内容', 'aksrt'))); ?></button>