Claude in Chrome: retry tabs_context_mcp with createIfEmpty after timeout

The first tabs_context_mcp call can time out while the extension wakes up. A plain retry then says the session has no tab group, and tabs_create_mcp refuses with the same error. Call tabs_context_mcp with createIfEmpty:true: it creates the group and returns a blank tab id. Navigate that tab directly instead of making a second tab, and close it with tabs_close_mcp at the end.