fix: 移除前端 API 环境入口

frontend/.env.example

@@ -1,5 +1,4 @@
 # Frontend feature flags and timeline overrides
-VITE_API_BASE_URL=
 VITE_STARTUP_SUBMIT_ACCEPT_TIMEOUT_MONTHS=3
 VITE_STARTUP_ACCEPT_TIMEOUT_MONTHS=3
 VITE_STARTUP_ACCEPT_APPROVAL_TIMEOUT_MONTHS=6

frontend/src/api/axios.ts

@@ -7,12 +7,9 @@ import { useStudyStore } from "../store/study";
 import { TEXT } from "../locales";
 import { extendAccessToken, forceLogout, lockSession, markNetworkActive } from "../session/sessionManager";
 import { useSessionStore } from "../store/session";
-import { resolveApiBaseUrl } from "./baseUrl";
-
-const apiBaseUrl = resolveApiBaseUrl(import.meta.env.VITE_API_BASE_URL);
 
 const instance: AxiosInstance = axios.create({
-  baseURL: apiBaseUrl,
+  baseURL: "/",
   timeout: 15000,
 });
 

frontend/src/api/baseUrl.test.ts

@@ -1,19 +0,0 @@
-import { describe, expect, it } from "vitest";
-import { resolveApiBaseUrl } from "./baseUrl";
-
-describe("resolveApiBaseUrl", () => {
-  it("defaults to same-origin root when no env override is set", () => {
-    expect(resolveApiBaseUrl(undefined)).toBe("/");
-    expect(resolveApiBaseUrl("")).toBe("/");
-    expect(resolveApiBaseUrl("   ")).toBe("/");
-  });
-
-  it("preserves explicit root", () => {
-    expect(resolveApiBaseUrl("/")).toBe("/");
-  });
-
-  it("trims whitespace and trailing slashes from absolute base urls", () => {
-    expect(resolveApiBaseUrl(" http://localhost:8000/ ")).toBe("http://localhost:8000");
-    expect(resolveApiBaseUrl("https://api.example.com///")).toBe("https://api.example.com");
-  });
-});

frontend/src/api/baseUrl.ts

@@ -1,12 +0,0 @@
-const trimTrailingSlashes = (value: string): string => value.replace(/\/+$/, "");
-
-export const resolveApiBaseUrl = (rawValue: string | undefined): string => {
-  const normalized = rawValue?.trim() ?? "";
-  if (!normalized) {
-    return "/";
-  }
-  if (normalized === "/") {
-    return "/";
-  }
-  return trimTrailingSlashes(normalized);
-};