Give the standalone promotion tab its own stylesheet and a task-priority
layout (成果概览 → 分享操作 → 奖励说明 → 邀请记录).
- assets/css/routes/user-center/promotion.css: new module owning all
uc-promotion-* rules; flattens #panel-promotion chrome, adds focus-visible
on the copy button + link input, and a ≤640px single-column layout with a
full-width copy button (no horizontal overflow)
- user-center.css: import the new promotion.css
- user-center/revenue.css: drop the now-migrated uc-promotion-* rules (keep
only the revenue-layout mobile rule)
- profile-invite.php: refresh doc header to describe the section priority
order; copy button stays a focusable <button>, credits.js keeps text-based
success/failure feedback via [data-invite-copy-feedback]
kate522
