feat: 백엔드 API 연동 (HTTP 클라이언트 + 홈 화면 실데이터)

- VITE_API_BASE_URL 기반 fetch 클라이언트 및 ApiError 처리
- api/spots, api/matches 타입드 모듈
- HomePage: 스팟/한줄평/메이트 실제 로드, 체크인·매칭 신청 API 연동
- 임시 세션 스토어(인증 도입 전, userId/dogId)
- 로딩/에러/빈 상태 처리

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/api/http.ts

@@ -0,0 +1,37 @@
+// 공통 HTTP 클라이언트 — VITE_API_BASE_URL 기준
+const BASE_URL = import.meta.env.VITE_API_BASE_URL ?? 'http://localhost:8080'
+
+export class ApiError extends Error {
+  constructor(
+    public status: number,
+    public code: string,
+    message: string,
+  ) {
+    super(message)
+    this.name = 'ApiError'
+  }
+}
+
+async function request<T>(method: string, path: string, body?: unknown): Promise<T> {
+  const res = await fetch(`${BASE_URL}${path}`, {
+    method,
+    headers: { 'Content-Type': 'application/json' },
+    body: body !== undefined ? JSON.stringify(body) : undefined,
+  })
+
+  const text = await res.text()
+  const data = text ? JSON.parse(text) : null
+
+  if (!res.ok) {
+    const code = (data && data.code) || 'ERROR'
+    const message = (data && data.message) || `요청 실패 (${res.status})`
+    throw new ApiError(res.status, code, message)
+  }
+
+  return data as T
+}
+
+export const http = {
+  get: <T>(path: string) => request<T>('GET', path),
+  post: <T>(path: string, body?: unknown) => request<T>('POST', path, body),
+}

src/api/matches.ts

@@ -0,0 +1,18 @@
+import { http } from './http'
+
+export interface Match {
+  id: number
+  requesterDogId: number
+  targetDogId: number
+  status: string
+  createdAt: string
+  respondedAt: string | null
+}
+
+export const matchesApi = {
+  create: (requesterDogId: number, targetDogId: number) =>
+    http.post<Match>('/api/matches', { requesterDogId, targetDogId }),
+  accept: (id: number) => http.post<Match>(`/api/matches/${id}/accept`),
+  reject: (id: number) => http.post<Match>(`/api/matches/${id}/reject`),
+  received: (dogId: number) => http.get<Match[]>(`/api/matches/received/${dogId}`),
+}

src/api/spots.ts

@@ -0,0 +1,39 @@
+import { http } from './http'
+
+export interface Spot {
+  id: number
+  name: string
+  type: string
+  latitude: number | null
+  longitude: number | null
+}
+
+export interface Mate {
+  dogId: number
+  name: string
+  breed: string | null
+}
+
+export interface Review {
+  id: number
+  tag: string | null
+  content: string | null
+  createdAt: string
+}
+
+export interface CheckInResult {
+  id: number
+  spotId: number
+  dogId: number
+  expiresAt: string
+}
+
+export const spotsApi = {
+  list: () => http.get<Spot[]>('/api/spots'),
+  mates: (spotId: number) => http.get<Mate[]>(`/api/spots/${spotId}/mates`),
+  reviews: (spotId: number) => http.get<Review[]>(`/api/spots/${spotId}/reviews`),
+  checkIn: (spotId: number, userId: number, dogId: number) =>
+    http.post<CheckInResult>(`/api/spots/${spotId}/checkins`, { userId, dogId }),
+  addReview: (spotId: number, userId: number, tag: string) =>
+    http.post<Review>(`/api/spots/${spotId}/reviews`, { userId, tag }),
+}