The Windows client sampled TAP diagnostics once when opening the adapter. That
can miss the useful DHCP result because the TAP interface may not receive a LAN
address until after frame bridging starts.
Keep the stable TAP diagnostics fields from startup, but retain the interface
identity and re-read the TAP unicast IP whenever the periodic diagnostics tick
prints and reports a snapshot. Later status lines can now show the DHCP address
that arrives after the tunnel is already moving traffic.
Test Plan:
- cargo fmt --check
- cargo test -p lanparty-client-win
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
- git diff --check
Refs: PLAN.md