fix(revenue): stop poster modal from blocking the whole revenue page

Two regressions from the previous commit made /user/revenue/ unusable.

The rewrite dropped data-aksrt-affiliate-poster-modal from the modal shell.
That single attribute was both the JS lookup key and the CSS hook, so
initAffiliatePoster() bailed at `if (!button || !modal) return` — which is
why the 推广海报 button never got un-hidden — and no CSS could target the
shell. Restore it.

With the shell back but still visible, main.css's .flex{display:flex} loads
after bootstrap and matches .modal{display:none} on specificity, so the
resting modal rendered as a full-viewport flex box. Combined with .fade's
opacity:0 that is an invisible overlay swallowing every click on the page.
Pin the resting state to display:none and the open state to flex, the same
way credits.css already does for the charge and points-pay modals — that
file documents this exact trap.

Add a contract test asserting the markup, JS selector and CSS hook share
one attribute and that the resting state is explicitly hidden.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/widget-system/referral-qr-contract.test.cjs

@@ -126,6 +126,23 @@ test('poster modal markup is a 1:1 replica of the reference poster-share dialog'
   assert.doesNotMatch(css, /uc-affiliate-poster/)
 })
 
+test('poster modal shell is hidden at rest so it cannot block the whole page', () => {
+  const modal = read('inc', 'helpers', 'user-center-renderers', 'affiliate-poster-modal.php')
+  const script = read('assets', 'js', 'credits.js')
+  const css = read('assets', 'css', 'routes', 'user-center', 'credits.css')
+
+  // 标记、JS 查询与 CSS 钩子必须共用同一个属性，缺一即失效：
+  // 少了标记上的属性，JS 拿不到弹窗、CSS 也隐藏不了它。
+  assert.match(modal, /data-aksrt-affiliate-poster-modal/)
+  assert.match(script, /querySelector\('\[data-aksrt-affiliate-poster-modal\]'\)/)
+
+  // 服务端静态输出的 .modal.flex 必须显式隐藏。main.css 的 .flex{display:flex}
+  // 后加载且与 bootstrap 的 .modal{display:none} 同特异性，不在此回位就会让
+  // 静止态弹窗铺满全屏，叠加 .fade 的 opacity:0 形成隐形遮罩、拦截整页点击。
+  assert.match(css, /\.modal\[data-aksrt-affiliate-poster-modal\]\s*\{\s*display:\s*none;/)
+  assert.match(css, /\.modal\[data-aksrt-affiliate-poster-modal\]\.in\s*\{\s*display:\s*flex;/)
+})
+
 test('invite-code input verifies live against the public REST endpoint', () => {
   const template = read('templates', 'parts', 'auth-content.php')
   assert.match(template, /data-invite-verify/)