fix: exclude wintun/tunnel virtual adapters from default interface detection on Windows

[bohid02]

Problem

On Windows, third-party applications (e.g., OPPO Connect, ZeroTier) can create wintun virtual adapters that register as IfType=6 (EthernetCSMACD) rather than IfType=53 (PropVirtual). The current checkUpdate() filter in monitor_windows.go only excludes IfTypePropVirtual and IfTypeSoftwareLoopback, so these third-party wintun adapters can be selected as the default outbound interface.

When this happens, mihomo's DIRECT outbound traffic is routed through the third-party wintun adapter instead of the physical NIC, causing traffic to loop back into the TUN and triggering reject loopback connection errors — resulting in complete network failure.

Root Cause

The wintun kernel driver (wintun.sys) registers all adapters as NDIS miniport with IfType=6 (Ethernet). The existing type-based filter cannot distinguish them from real physical adapters:

// current code - does not catch wintun devices
if ifrow.Type == winipcfg.IfTypePropVirtual || ifrow.Type == winipcfg.IfTypeSoftwareLoopback {
    continue
}

Fix

Add a Description-based filter to exclude adapters whose InterfaceDescription contains "Wintun" or "Tunnel". These are virtual tunnel adapters and should never be selected as the default outbound interface.

Reproduction

1. Install any application that creates a wintun adapter (e.g., OPPO Connect creates ROOT\WINTUN\0000)
2. Enable TUN mode with auto-route: true
3. All network traffic fails with reject loopback connection errors
4. Removing the third-party wintun device with pnputil /remove-device immediately resolves the issue

Verification

• Tested on Windows 11 with OPPO Connect (O+Connect) installed
• OPPO Connect's wintun device: ROOT\WINTUN\0000, Description = "Wintun Userspace Tunnel", IfType=6, InterfaceMetric=5
• After applying this fix, the third-party wintun adapter is correctly excluded from default interface detection

Related

• 提供一个tun模式无法联网的案例参考（oppo 互联） clash-verge-rev/clash-verge-rev#6712