优化多个页面样式及组件功能，优化课程、发现、训练、首页等核心页面样式

gym-manage-uniapp/pages/course/index.vue

@@ -126,7 +126,7 @@ function goMyCourses() {
 <style lang="scss" scoped>
 .tab-page {
   min-height: 100vh;
-  background-color: #f0f4f8;
+  background: $gradient-sky;
   padding-bottom: 160rpx;
 }
 
@@ -137,15 +137,15 @@ function goMyCourses() {
 .tab-page__title {
   display: block;
   font-size: 40rpx;
-  font-weight: 700;
-  color: #1a202c;
+  font-weight: $font-weight-bold;
+  color: $text-dark;
 }
 
 .tab-page__subtitle {
   display: block;
   margin-top: 8rpx;
   font-size: 24rpx;
-  color: #64748b;
+  color: $text-muted;
 }
 
 .tab-page__actions {
@@ -157,26 +157,34 @@ function goMyCourses() {
 .tab-page__btn {
   flex: 1;
   height: 80rpx;
-  border-radius: 999rpx;
-  background: linear-gradient(135deg, #ff6b35 0%, #ff8c5a 100%);
+  border-radius: $radius-full;
+  background: $gradient-orange;
   display: flex;
   align-items: center;
   justify-content: center;
+  box-shadow: $shadow-orange-glow;
+  transition: all 0.2s ease;
+}
+
+.tab-page__btn:active {
+  transform: scale(0.97);
+  background: $accent-orange-dark;
 }
 
 .tab-page__btn--ghost {
-  background: #fff;
-  border: 1px solid #e2e8f0;
+  background: $bg-white;
+  border: 1px solid $border-light;
+  box-shadow: $shadow-sm;
 }
 
 .tab-page__btn-text {
   font-size: 28rpx;
-  font-weight: 600;
-  color: #fff;
+  font-weight: $font-weight-bold;
+  color: $text-inverse;
 }
 
 .tab-page__btn-text--ghost {
-  color: #1a4a6f;
+  color: $primary-deep;
 }
 
 .bottom-placeholder {
@@ -191,8 +199,9 @@ function goMyCourses() {
 .skeleton-item {
   margin-bottom: 24rpx;
   padding: 20rpx;
-  background: #fff;
-  border-radius: 20rpx;
+  background: $bg-white;
+  border-radius: $radius-md;
+  box-shadow: $shadow-sm;
 }
 
 .skeleton-img {
@@ -201,7 +210,7 @@ function goMyCourses() {
   background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
   background-size: 200% 100%;
   animation: skeleton-loading 1.5s infinite;
-  border-radius: 16rpx;
+  border-radius: $radius-sm;
 }
 
 .skeleton-text {