Add frontend POI management and travel time display

POIManager component in FilterPanel for creating/deleting POIs and
triggering distance calculations. PropertyCard shows travel time badges
(walk/cycle/transit) per POI. Map renders POI locations as red markers.
API client extended with POST body support for POI endpoints.

frontend/src/services/apiClient.ts

@@ -6,6 +6,7 @@ import { ApiError } from '@/types';
 export interface RequestOptions {
   method?: 'GET' | 'POST' | 'PUT' | 'DELETE';
   params?: Record<string, string | number | boolean | Date | undefined>;
+  body?: unknown;
 }
 
 /**
@@ -35,7 +36,7 @@ export async function apiRequest<T>(
   endpoint: string,
   options: RequestOptions = {}
 ): Promise<T> {
-  const { method = 'GET', params } = options;
+  const { method = 'GET', params, body } = options;
 
   let url = endpoint;
   if (params) {
@@ -45,13 +46,19 @@ export async function apiRequest<T>(
     }
   }
 
-  const response = await fetch(url, {
+  const fetchOptions: RequestInit = {
     method,
     headers: {
       Authorization: `Bearer ${user.accessToken}`,
       'Content-Type': 'application/json',
     },
-  });
+  };
+
+  if (body !== undefined) {
+    fetchOptions.body = JSON.stringify(body);
+  }
+
+  const response = await fetch(url, fetchOptions);
 
   if (!response.ok) {
     throw new ApiError(`Error: ${response.status}`, response.status);

frontend/src/services/index.ts

@@ -4,3 +4,4 @@ export { fetchListingGeoJSON, refreshListings } from './listingService';
 export { streamListingGeoJSON, type StreamingProgress } from './streamingService';
 export { fetchTasksForUser, fetchTaskStatus, cancelTask, clearAllTasks, type CancelTaskResponse, type ClearAllTasksResponse } from './taskService';
 export { checkBackendHealth, type HealthStatus, type HealthCheckResult } from './healthService';
+export { fetchUserPOIs, createPOI, updatePOI, deletePOI, triggerPOICalculation, fetchPOIDistances } from './poiService';

frontend/src/services/poiService.ts

@@ -0,0 +1,64 @@
+// POI API service for managing Points of Interest
+
+import type { AuthUser } from '@/auth/types';
+import type { POI, POIDistanceInfo } from '@/types';
+import { apiRequest } from './apiClient';
+
+export async function fetchUserPOIs(user: AuthUser): Promise<POI[]> {
+  return apiRequest<POI[]>(user, '/api/poi');
+}
+
+export async function createPOI(
+  user: AuthUser,
+  data: { name: string; address: string; latitude: number; longitude: number }
+): Promise<POI> {
+  return apiRequest<POI>(user, '/api/poi', {
+    method: 'POST',
+    body: data,
+  });
+}
+
+export async function updatePOI(
+  user: AuthUser,
+  poiId: number,
+  data: { name?: string; address?: string; latitude?: number; longitude?: number }
+): Promise<POI> {
+  return apiRequest<POI>(user, `/api/poi/${poiId}`, {
+    method: 'PUT',
+    body: data,
+  });
+}
+
+export async function deletePOI(user: AuthUser, poiId: number): Promise<void> {
+  await apiRequest(user, `/api/poi/${poiId}`, { method: 'DELETE' });
+}
+
+export async function triggerPOICalculation(
+  user: AuthUser,
+  poiId: number,
+  travelModes: string[],
+  listingType: 'RENT' | 'BUY',
+  listingIds?: number[]
+): Promise<{ task_id: string; message: string }> {
+  return apiRequest(user, `/api/poi/${poiId}/calculate`, {
+    method: 'POST',
+    body: {
+      travel_modes: travelModes,
+      listing_type: listingType,
+      listing_ids: listingIds,
+    },
+  });
+}
+
+export async function fetchPOIDistances(
+  user: AuthUser,
+  listingId: number,
+  listingType: 'RENT' | 'BUY' = 'RENT'
+): Promise<POIDistanceInfo[]> {
+  return apiRequest<POIDistanceInfo[]>(user, '/api/poi/distances', {
+    params: {
+      listing_id: listingId,
+      listing_type: listingType,
+    },
+  });
+}