fix: 修复所有超时设置0=禁用不生效的问题

1. 流式超时: baseTimeout=0时被忽略，仍走动态计算120s-600s 2. HTTP超时: ipc.ts中0>0=false导致setHTTPTimeout未调用 + Math.max(5000,ms)阻止0值 3. MCP超时: 同HTTP模式 + Math.max(10000,ms)阻止0值 4. fetchWithTimeout和web_fetch中直接setTimeout在HTTP_TIMEOUT=0时仍触发abort

src/main/ipc.ts

@@ -262,10 +262,10 @@ export async function setupIPC(): Promise<void> {
   });
 
   ipcMain.handle('tool:setTimeouts', (_, timeouts: { http?: number; mcp?: number }) => {
-    if (typeof timeouts.http === 'number' && timeouts.http > 0) {
+    if (typeof timeouts.http === 'number' && timeouts.http >= 0) {
       setHTTPTimeout(timeouts.http);
     }
-    if (typeof timeouts.mcp === 'number' && timeouts.mcp > 0) {
+    if (typeof timeouts.mcp === 'number' && timeouts.mcp >= 0) {
       setMCPTimeout(timeouts.mcp);
     }
     return { success: true };