fix: 前端 API 调用改为相对路径，通过 Vite 代理避免 CORS

前端 5 个文件中硬编码了 http://localhost:8080 绝对路径，
浏览器从 127.0.0.1:5173 访问时触发 CORS 预检失败。
改为相对路径 /api/v1/... 通过 Vite 代理转发，
WebSocket URL 改为动态构造（基于当前页面 host）。

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/web/src/api/client.ts

@@ -2,7 +2,7 @@
 
 import type { AuthResponse } from '@/types/session';
 
-const API_BASE_URL = import.meta.env.VITE_API_URL || 'http://localhost:8080/api/v1';
+const API_BASE_URL = import.meta.env.VITE_API_URL || '/api/v1';
 
 /** localStorage key 前缀 */
 const LS_TOKEN_KEY = 'token';

frontend/web/src/api/files.ts

@@ -38,7 +38,7 @@ interface FileResponse {
   thumbnail_url?: string;
 }
 
-const API_BASE = import.meta.env.VITE_API_URL || 'http://localhost:8080/api/v1';
+const API_BASE = import.meta.env.VITE_API_URL || '/api/v1';
 
 /**
  * 获取带授权头的文件下载/缩略图 URL (用于 fetch 直接获取 blob)

frontend/web/src/api/sessions.ts

@@ -170,7 +170,7 @@ export async function exportSession(
 ): Promise<void> {
   const token = localStorage.getItem('token');
   const resp = await fetch(
-    `${import.meta.env.VITE_API_URL || 'http://localhost:8080/api/v1'}/sessions/${encodeURIComponent(sessionId)}/export?format=${format}`,
+    `${import.meta.env.VITE_API_URL || '/api/v1'}/sessions/${encodeURIComponent(sessionId)}/export?format=${format}`,
     {
       headers: {
         Authorization: `Bearer ${token}`,

frontend/web/src/api/voice.ts

@@ -73,7 +73,7 @@ async function transcribeAudio(audioBlob: Blob, language?: string): Promise<ApiR
   // 不设置 Content-Type，让浏览器自动处理 multipart boundary
 
   try {
-    const response = await fetch('http://localhost:8080/api/v1/voice/transcribe', {
+    const response = await fetch('/api/v1/voice/transcribe', {
       method: 'POST',
       headers,
       body: formData,
@@ -110,7 +110,7 @@ async function synthesizeSpeech(req: TTSSynthesizeRequest): Promise<string> {
     headers['Authorization'] = `Bearer ${token}`;
   }
 
-  const response = await fetch('http://localhost:8080/api/v1/voice/tts', {
+  const response = await fetch('/api/v1/voice/tts', {
     method: 'POST',
     headers,
     body: JSON.stringify(req),

frontend/web/src/hooks/useWebSocket.ts

@@ -5,8 +5,11 @@ import { useNotificationStore } from '@/store/notificationStore';
 import { getToken } from '@/api/client';
 import type { Message, WSClientMessage, WSServerMessage } from '@/types/chat';
 
-const WS_BASE_URL =
-  import.meta.env.VITE_WS_URL || 'ws://localhost:8080/ws/chat';
+function getWsUrl(): string {
+  if (import.meta.env.VITE_WS_URL) return import.meta.env.VITE_WS_URL;
+  const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
+  return `${protocol}//${window.location.host}/ws/chat`;
+}
 
 // ========== 指数退避重连配置 ==========
 const INITIAL_RECONNECT_DELAY_MS = 1000; // 初始延迟 1 秒
@@ -77,8 +80,8 @@ export function useWebSocket() {
 
     const sessionID = useSessionStore.getState().currentSessionId || '';
     const url = sessionID
-      ? `${WS_BASE_URL}?token=${token}&session_id=${sessionID}`
-      : `${WS_BASE_URL}?token=${token}`;
+      ? `${getWsUrl()}?token=${token}&session_id=${sessionID}`
+      : `${getWsUrl()}?token=${token}`;
 
     console.log(`[WS#${instanceId}] 正在连接, session_id=${sessionID || '(无)'}, reconnectAttempt=${reconnectCountRef.current}`);
     const ws = new WebSocket(url);