feat(web): 工作台 AI 模式与差旅/风险建议交互优化

- 新增 PersonalWorkbenchAiMode 组件、AI 侧边栏与 orb 机器人视觉资源
- 新增 aiApplicationDraftModel / aiExpenseDraftModel / aiWorkbenchConversationStore
  及业务准入 aiSidebarBusinessAccess，支撑 AI 模式下的申请与报销草稿
- 顶栏、侧边栏、工作台样式重构，适配 AI 模式切换与响应式布局
- 同步 steward plan/off_topic、差旅报销引导流、风险建议卡片等测试

web/src/assets/styles/components/top-bar.css

@@ -380,6 +380,14 @@
   min-width: 0;
 }
 
+.topbar-utility-actions {
+  display: inline-flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: 10px;
+  min-width: 0;
+}
+
 .topbar-icon-btn {
   position: relative;
   width: 34px;
@@ -1113,6 +1121,68 @@
   font-size: 16px;
 }
 
+.topbar-ai-mode-toggle {
+  flex: 0 0 38px;
+  width: 38px;
+  height: 38px;
+  display: inline-grid;
+  place-items: center;
+  padding: 0;
+  border: 2px solid transparent;
+  border-radius: 50%;
+  background:
+    linear-gradient(#ffffff, #ffffff) padding-box,
+    conic-gradient(from 210deg, #15b8c8, #4f6fef, #b65cff, #ec4899, #f59e0b, #15b8c8) border-box;
+  box-shadow:
+    0 8px 18px rgba(79, 111, 239, 0.16),
+    0 0 0 1px rgba(255, 255, 255, 0.78) inset;
+  transition:
+    transform 180ms var(--ease),
+    box-shadow 180ms var(--ease),
+    filter 180ms var(--ease);
+}
+
+.topbar-ai-mode-toggle__glyph {
+  display: inline-block;
+  background: linear-gradient(135deg, #0ea5b7 4%, #4f6fef 34%, #a855f7 58%, #ec4899 76%, #f59e0b 96%);
+  background-clip: text;
+  -webkit-background-clip: text;
+  color: transparent;
+  font-size: 15px;
+  font-weight: 950;
+  line-height: 1;
+  letter-spacing: 0;
+}
+
+.topbar-ai-mode-toggle:hover,
+.topbar-ai-mode-toggle:focus-visible {
+  transform: translateY(-1px);
+  box-shadow:
+    0 12px 24px rgba(79, 111, 239, 0.2),
+    0 0 0 4px rgba(236, 72, 153, 0.08),
+    0 0 0 1px rgba(255, 255, 255, 0.86) inset;
+}
+
+.topbar-ai-mode-toggle:focus-visible {
+  outline: 2px solid color-mix(in srgb, var(--theme-primary-active) 72%, #ffffff);
+  outline-offset: 3px;
+}
+
+.topbar-ai-mode-toggle.active {
+  filter: saturate(1.1);
+  box-shadow:
+    0 12px 24px rgba(79, 111, 239, 0.22),
+    0 0 0 4px rgba(14, 165, 183, 0.09),
+    0 0 0 1px rgba(255, 255, 255, 0.88) inset;
+}
+
+.topbar-ai-mode-toggle:not(.active) {
+  filter: saturate(0.82);
+  box-shadow:
+    0 6px 14px rgba(15, 23, 42, 0.1),
+    0 0 0 1px rgba(255, 255, 255, 0.82) inset;
+}
+
 .kpi-chip {
   display: grid;
   grid-template-columns: auto auto;
@@ -1259,6 +1329,10 @@
     gap: 12px;
   }
 
+  .topbar-utility-actions {
+    gap: 8px;
+  }
+
   .topbar-icon-btn {
     width: 30px;
     height: 30px;
@@ -1271,6 +1345,16 @@
     font-size: 12px;
   }
 
+  .topbar-ai-mode-toggle {
+    flex: 0 0 34px;
+    width: 34px;
+    height: 34px;
+  }
+
+  .topbar-ai-mode-toggle__glyph {
+    font-size: 14px;
+  }
+
   .kpi-chips {
     gap: 8px;
   }
@@ -1329,6 +1413,7 @@
   .search-wrap,
   .search-wrap.wide,
   .topbar-toolset,
+  .topbar-utility-actions,
   .detail-alert-strip,
   .month-chip,
   .qa-filter,
@@ -1344,6 +1429,15 @@
     justify-content: flex-end;
   }
 
+  .topbar-utility-actions {
+    justify-content: flex-end;
+  }
+
+  .topbar-ai-mode-toggle {
+    width: 34px;
+    height: 34px;
+  }
+
   .range-shell {
     flex: 1;
   }
@@ -1505,6 +1599,10 @@
     justify-content: space-between;
   }
 
+  .topbar-ai-mode-toggle {
+    flex: 0 0 34px;
+  }
+
   .range-combo {
     display: grid;
     gap: 8px;