feat(travel): 接入远端 AI 推荐服务，支持 GLM real 模式与本地静默回退

- createPlan 在配置 VITE_TRAVEL_ASSISTANT_API_BASE_URL 时调用 FastAPI 推荐服务
  做无坐标选点，路线/交通/时长仍由本机核算；远端不可用即静默回退本地规划
- 放开 loadPlan 对远端行程的回读限制（原 AI 冻结期禁用），行程页跳转不再丢行程
- planner/assistant 文案按是否启用远端如实切换，不再谎称「本期不调用 AI」
- 新增远端接通/回退/候选载荷单测；server/README 更新联调与 real 模式说明
- .env.development 默认指向已部署推荐服务；server/.env.example 补 GLM 示例

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

src/services/travel-assistant/service.ts

@@ -1,17 +1,25 @@
+import type { PoiRepository } from '@/domain/poi'
 import { getPoiRepository } from '@/data/poi'
 import {
   adjustLocalPlan,
   clonePlanResponse,
   cloneTravelPreferences,
   createLocalPlan,
+  createRecommendedPlan,
   normalizePlanningRequest,
   normalizeTravelPreferences,
   type PlanningOrigin,
+  type PlanningRecommendation,
   type PlanningRequest,
   type PlanResponse,
   type TravelPreferences,
   TravelValidationError,
 } from '@/domain/travel'
+import {
+  createRemoteRecommendations,
+  isRemoteTravelAssistantEnabled,
+  type RemotePoiCandidateInput,
+} from './remote'
 import { loadPlan, loadPlanningRequest, loadPreferences, savePlanningRequest, savePreferences } from './storage'
 
 interface LocalSession {
@@ -82,6 +90,38 @@ function isPlanningRequest(input: TravelPreferences | PlanningRequest): input is
   return typeof input === 'object' && input !== null && 'mode' in input && 'preferences' in input
 }
 
+/**
+ * Builds the coordinate-free POI candidate whitelist sent to the remote service.
+ * Quick mode offers every published POI; custom mode offers only the user's picks.
+ * No coordinates ever leave the client.
+ */
+function buildRemoteCandidates(repository: PoiRepository, request: PlanningRequest): RemotePoiCandidateInput[] {
+  const pois = request.mode === 'custom'
+    ? request.selectedPoiIds.flatMap(poiId => repository.getPoiById(poiId) ?? [])
+    : repository.getPublishedPois()
+  return pois.map(poi => ({
+    id: poi.id,
+    name: poi.name,
+    categoryCode: poi.categoryCode,
+    tagCodes: poi.tagCodes,
+    summary: poi.summary,
+    recommendationIndex: poi.recommendationIndex,
+  }))
+}
+
+/** Asks the remote service for POI recommendations, then schedules them locally. */
+async function createRemotePlan(
+  request: PlanningRequest,
+  repository: PoiRepository,
+): Promise<PlanResponse> {
+  const candidates = buildRemoteCandidates(repository, request)
+  const remote = await createRemoteRecommendations(request, candidates)
+  // Array order is the suggested visit order; reasons travel with each POI.
+  const recommendations: PlanningRecommendation[] = remote.recommendations.map(({ poiId, reason }) => ({ poiId, reason }))
+  const source = remote.generationMode === 'real' ? 'remote_ai' : 'remote_mock'
+  return createRecommendedPlan(request, recommendations, repository, remote.assistantMessage, source)
+}
+
 export function createPlan(input: PlanningRequest): Promise<PlanResponse>
 export function createPlan(input: TravelPreferences, planningOrigin?: PlanningOrigin): Promise<PlanResponse>
 export async function createPlan(
@@ -98,7 +138,23 @@ export async function createPlan(
         selectedPoiIds: [],
         ...(normalizePlanningOrigin(planningOrigin) ? { origin: normalizePlanningOrigin(planningOrigin)! } : {}),
       }, repository)
+
+  if (isRemoteTravelAssistantEnabled()) {
+    try {
+      const plan = await createRemotePlan(request, repository)
+      rememberLocalSession(plan, request)
+      savePlanningRequest(request)
+      return clonePlanResponse(plan, repository)
+    }
+    catch (error) {
+      // Resilient POC default: never block the demo on a remote hiccup.
+      console.warn('Remote travel assistant unavailable, falling back to local planner', error)
+    }
+  }
+
   const plan = createLocalPlan(request, repository)
+  if (isRemoteTravelAssistantEnabled())
+    plan.assistantMessage = '远程行程服务暂不可用，已改用本机确定性规划生成路线。'
   rememberLocalSession(plan, request)
   savePlanningRequest(request)
   return clonePlanResponse(plan, repository)