perf: 完善黑夜模式的表现效果，工作流编排幕布和节点在黑夜模式正常表现

easyflow-ui-admin/packages/tinyflow-ui/src/components/base/collapse.svelte

@@ -91,8 +91,8 @@
         width: 16px;
         height: 16px;
         border-radius: 50%;
-        border: 1px solid #c6cfdd;
-        color: #64748b;
+        border: 1px solid var(--tf-border-color-strong);
+        color: var(--tf-text-secondary);
         display: inline-flex;
         align-items: center;
         justify-content: center;
@@ -100,14 +100,14 @@
         line-height: 1;
         cursor: default;
         user-select: none;
-        background: #fff;
+        background: var(--tf-bg-surface);
         position: relative;
     }
 
     .tf-collapse-item-title-help:hover {
-        border-color: #94a3b8;
-        color: #334155;
-        background: #f8fafc;
+        border-color: var(--tf-border-color-strong);
+        color: var(--tf-text-primary);
+        background: var(--tf-bg-hover);
     }
 
     .tf-collapse-item-title-help::after {
@@ -119,13 +119,13 @@
         min-width: 260px;
         max-width: 420px;
         white-space: pre-line;
-        background: #0f172a;
-        color: #f8fafc;
+        background: var(--tf-tip-bg);
+        color: var(--tf-tip-text);
         border-radius: 8px;
         padding: 10px 12px;
         font-size: 12px;
         line-height: 1.45;
-        box-shadow: 0 8px 22px rgba(2, 6, 23, 0.25);
+        box-shadow: var(--tf-shadow-medium);
         opacity: 0;
         visibility: hidden;
         pointer-events: none;
@@ -140,7 +140,7 @@
         transform: translateY(-50%);
         border-top: 6px solid transparent;
         border-bottom: 6px solid transparent;
-        border-right: 6px solid #0f172a;
+        border-right: 6px solid var(--tf-tip-bg);
         opacity: 0;
         visibility: hidden;
         z-index: 121;