feat(fe): 肉垫 FAB + 冷启动闪屏；顶部筛选改纯文字对齐

- FAB 重设计成肉垫造型（呼应「肉垫计划」），修 fab.js 漏声明
  icon 属性导致的兜底文档图标；社区发帖 FAB 保持图标
- onboarding 加冷启动闪屏，登录+拉宠物在闪屏期完成再进首页，
  不再闪一下建档向导；欢迎屏 logo 换肉垫、去掉过时 AI 文案
- 顶部宠物筛选去掉头像改纯文字（带图/emoji 时高度对不齐），
  固定高度 + vertical-align:middle 彻底对齐，添加用「＋」文字

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

pets-fe/pages/onboarding/onboarding.wxss

@@ -9,13 +9,46 @@
 .skip-link{text-align:center;margin-top:var(--sp-4);color:var(--muted);font-size:var(--fs-md);padding:var(--sp-2)}
 @keyframes fade{from{opacity:0;transform:translateY(16rpx)}to{opacity:1;transform:none}}
 
+/* 冷启动闪屏 */
+.boot{
+  position:fixed;inset:0;z-index:200;
+  display:flex;flex-direction:column;align-items:center;justify-content:center;
+  background:
+    radial-gradient(circle at 50% 32%, rgba(253,179,92,.28), transparent 55%),
+    var(--bg);
+}
+.boot-badge{
+  width:184rpx;height:184rpx;border-radius:44rpx;
+  background:linear-gradient(150deg,#FFB865,#F5943E);
+  display:flex;align-items:center;justify-content:center;
+  box-shadow:0 18rpx 42rpx rgba(214,138,52,.4);
+  animation:boot-pop .5s ease both, boot-breathe 2.4s ease-in-out .5s infinite;
+}
+.boot-name{margin-top:var(--sp-5);font-size:var(--fs-2xl);font-weight:var(--fw-b);letter-spacing:-1rpx}
+.boot-tip{margin-top:var(--sp-2);color:var(--muted);font-size:var(--fs-md)}
+@keyframes boot-pop{from{opacity:0;transform:scale(.8)}to{opacity:1;transform:scale(1)}}
+@keyframes boot-breathe{0%,100%{transform:translateY(0)}50%{transform:translateY(-10rpx)}}
+
 .hero{text-align:center;padding:60rpx 0 var(--sp-5)}
 .pet-logo{
   width:176rpx;height:176rpx;margin:0 auto var(--sp-5);border-radius:var(--r-lg);
-  background:linear-gradient(135deg,#FFE0AB,#FDB35C);
-  display:flex;align-items:center;justify-content:center;font-size:88rpx;
+  background:linear-gradient(135deg,#FFB865,#F5943E);
+  display:flex;align-items:center;justify-content:center;
   box-shadow:var(--sd-2);
 }
+
+/* 肉垫（呼应「肉垫计划」）——奶白掌垫 + 四趾垫，闪屏和欢迎屏共用 */
+.paw{position:relative;width:100rpx;height:92rpx}
+.paw .pad{
+  position:absolute;left:50%;bottom:0;transform:translateX(-50%);
+  width:66rpx;height:54rpx;background:#FFF7EC;
+  border-radius:48% 48% 44% 44%/62% 62% 40% 40%;
+}
+.paw .bean{position:absolute;background:#FFF7EC;border-radius:50%}
+.paw .bean-1{width:22rpx;height:30rpx;left:0;top:30rpx;transform:rotate(-20deg)}
+.paw .bean-2{width:24rpx;height:33rpx;left:27rpx;top:6rpx;transform:rotate(-7deg)}
+.paw .bean-3{width:24rpx;height:33rpx;right:27rpx;top:6rpx;transform:rotate(7deg)}
+.paw .bean-4{width:22rpx;height:30rpx;right:0;top:30rpx;transform:rotate(20deg)}
 .hero-h1{font-size:var(--fs-2xl);letter-spacing:-1.2rpx;font-weight:var(--fw-b)}
 .hero-sub{margin-top:var(--sp-3);line-height:1.65;color:var(--muted);font-size:var(--fs-md)}