fix: 恢复本地 Convex Auth 链路

- 修复 desktop 脚本在 Linux 下优先使用后端虚拟环境可执行文件
- 移除 Convex Auth 的本地密钥兜底，回到真实 deployment env
- 首页未登录时先跳转 /auth，避免根路由直接触发 workspace 初始化失败

scripts/desktop-prod.js

@@ -29,8 +29,34 @@ const backendDir = path.join(rootDir, "wolai-backend");
 const ingestDir = path.join(rootDir, "services", "ingest_service");
 const ragGatewayDir = path.join(rootDir, "services", "rag_gateway");
 
-const pythonBin = process.env.PYTHON_BIN || "python";
-const celeryBin = process.env.CELERY_BIN || "celery";
+function resolveBackendExecutable(envName, fallbackName) {
+  const fromEnv = (process.env[envName] || "").trim();
+  if (fromEnv) return fromEnv;
+
+  const isWin = process.platform === "win32";
+  const candidates = isWin
+    ? [
+        path.join(backendDir, ".venv", "Scripts", `${fallbackName}.exe`),
+        path.join(backendDir, ".venv312", "Scripts", `${fallbackName}.exe`),
+        path.join(backendDir, "venv", "Scripts", `${fallbackName}.exe`),
+      ]
+    : [
+        path.join(backendDir, ".venv-linux", "bin", fallbackName),
+        path.join(backendDir, ".venv", "bin", fallbackName),
+        path.join(backendDir, "venv", "bin", fallbackName),
+      ];
+
+  for (const candidate of candidates) {
+    if (fs.existsSync(candidate)) {
+      return candidate;
+    }
+  }
+
+  return fallbackName;
+}
+
+const pythonBin = resolveBackendExecutable("PYTHON_BIN", "python");
+const celeryBin = resolveBackendExecutable("CELERY_BIN", "celery");
 const skipCelery =
   (process.env.SKIP_CELERY || "").toLowerCase() === "1" ||
   (process.env.SKIP_CELERY || "").toLowerCase() === "true";