xlab-gateway: fix IPv6 routing, clean up table names
...
- Remove IPv6 default route from freedom table (1002) — wgnet peer
doesn't forward IPv6, causing TLS resets on outbound connections
- Remove Tsinghua IPv6 throw route (unnecessary without IPv6 default)
- IPv6 now uses native WAN path instead of WireGuard tunnel
- Rename table 1002 from typo 'wg-to-skywme' to 'freedom-wgnet'
Co-Authored-By: Claude Opus 4.6 <[email protected]>