feat(web): update views and services

Views:
- AppShellRouteView.vue: update route view
- SettingsView.vue: update settings view
- TravelReimbursementCreateView.vue: update travel form view
- scripts/SettingsView.js: update settings view logic
- scripts/TravelReimbursementCreateView.js: update travel form logic

Services:
- services/orchestrator.js: update orchestrator service client

web/src/views/SettingsView.vue

@@ -181,10 +181,71 @@
                 </button>
               </div>
             </section>
-          </template>
-
-          <template v-else-if="activeSection === 'llm'">
-            <div class="model-grid">
+          </template>
+
+          <template v-else-if="activeSection === 'session'">
+            <section class="settings-card">
+              <div class="card-head">
+                <div>
+                  <h4>会话保留策略</h4>
+                  <p>控制智能体会话在系统中的保留时长，超过保留期的历史会话会自动清理。</p>
+                </div>
+              </div>
+
+              <div class="form-grid compact-grid">
+                <label class="field">
+                  <span><em>*</em> 保留会话天数</span>
+                  <div
+                    ref="sessionRetentionPickerRef"
+                    class="session-picker-filter"
+                    :class="{ open: sessionRetentionPickerOpen }"
+                  >
+                    <button
+                      class="session-picker-trigger"
+                      type="button"
+                      :aria-expanded="sessionRetentionPickerOpen"
+                      aria-haspopup="dialog"
+                      @click="toggleSessionRetentionPicker"
+                    >
+                      <span class="session-picker-label">{{ pageState.sessionForm.conversationRetentionDays }} 天</span>
+                      <i class="mdi mdi-chevron-down"></i>
+                    </button>
+
+                    <div
+                      v-if="sessionRetentionPickerOpen"
+                      class="session-picker-popover"
+                      role="dialog"
+                      aria-label="选择会话保留天数"
+                    >
+                      <header>
+                        <strong>选择会话保留天数</strong>
+                        <button type="button" aria-label="关闭会话保留天数选择" @click="closeSessionRetentionPicker">
+                          <i class="mdi mdi-close"></i>
+                        </button>
+                      </header>
+
+                      <div class="session-picker-option-list">
+                        <button
+                          v-for="option in sessionRetentionOptions"
+                          :key="option.value"
+                          type="button"
+                          class="session-picker-option"
+                          :class="{ active: pageState.sessionForm.conversationRetentionDays === option.value }"
+                          @click="selectSessionRetentionDays(option.value)"
+                        >
+                          {{ option.label }}
+                        </button>
+                      </div>
+                    </div>
+                  </div>
+                  <small>最小 1 天，最大 10 天，按会话最后活跃时间计算。</small>
+                </label>
+              </div>
+            </section>
+          </template>
+
+          <template v-else-if="activeSection === 'llm'">
+            <div class="model-grid">
               <section class="settings-card">
                 <div class="card-head">
                   <div>