Windows 7 doesn't support Bluetooth LE in the OS. It may support Bluetooth, but it needs to be Bluetooth LE. If you managed to pair, chances are it was through some driver software provided by the Bluetooth radio manufacturer - that might handle Bluetooth LE keyboards, but it won't allow the Web IDE access to the device.
So you need to allow the Espruino Native IDE to have full access to the Bluetooth radio itself, without going through windows. You have two options:
- Disable Bluetooth in Windows by using Zadig to install the WinUSB driver for your built-in Bluetooth (not recommended, as you're disabling Bluetooth in Windows)
- Get a Bluetooth LE USB dongle like recommended here and use zadig to configure it for use with WinUSB so the IDE can use it. You then get to keep the existing Bluetooth support in the Laptop.
Windows 8.1 and later do have Bluetooth LE support in the OS, but I'm afraid Windows 7 doesn't. It was released 10 years ago - before the Bluetooth LE spec was released.