fix(ci): lint clean — %w wrapping in VerifyDescriptor + nilerr in proxyRelayConnections
- portal/discovery/sign.go: errorlint flagged three fmt.Errorf calls that used %v for wrapped errors after a leading %w. Switched to multi-%w (Go 1.20+) so callers can errors.Is both the sentinel and the underlying cause. - cmd/portal-tunnel/relays.go: nilerr flagged the accept-loop returning nil when ctx.Err() != nil — the err value was discarded. Reordered the switch so only context.Canceled returns nil (documented shutdown), other ctx errors surface via ctx.Err(). Note: golangci-lint pre-commit hook SKIPped — its isolated toolchain pins go 1.26.1 but go.mod requires 1.26.2 (environment drift). Verified locally with go 1.26.2 + golangci-lint 2.11.4: 0 issues across all CI-targeted packages. CI will re-run the check with the correct toolchain.