Add defer cleanup to NewGTU7 to prevent serial port leak

[Copilot]

Addresses resource leak in NewGTU7 where a panic after successful OpenSerial would leave the port open.

Changes

• Added defer cleanup pattern using ok flag to close serial port on panic
• Follows established pattern from drivers/serial_linux.go:30-35

port, err := cfg.Factory.OpenSerial(cfg.Serial)
if err != nil {
    panic(err)
}

// Ensure we don't leak the port if a panic occurs after opening.
ok := false
defer func() {
    if !ok {
        if closer, canClose := port.(io.Closer); canClose {
            _ = closer.Close()
        }
    }
}()

r = port
ok = true

The type assertion to io.Closer handles both SerialPort returns and any future interface changes.

---

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• go.googlesource.com
  • Triggering command: /update-job-proxy /update-job-proxy 4303997/b011/ (dns block)
  • Triggering command: /update-job-proxy /update-job-proxy -o br-d8f236fa6d57 -j DROP ertum_EC-384_CA.pem .8/x64/codeql/to/usr/share/ca-certificates/mozilla/Security_Communication_ECC_RootCA1.crt test eUeXgd7p LBT77L5xt rgo/bin/git test -e 2888f65.0 AIKBV6smDMe5S/ne/usr/share/ca-certificates/mozilla/emSign_ECC_Root_CA_-_G3.crt /usr/bin/test a56daae944d3c60c/usr/sbin/iptables ication_Authorit--wait ache/go/1.24.11/-t test (dns block)
• gopkg.in
  • Triggering command: /update-job-proxy /update-job-proxy 4303997/b011/ (dns block)
  • Triggering command: /update-job-proxy /update-job-proxy -o br-d8f236fa6d57 -j DROP ertum_EC-384_CA.pem .8/x64/codeql/to/usr/share/ca-certificates/mozilla/Security_Communication_ECC_RootCA1.crt test eUeXgd7p LBT77L5xt rgo/bin/git test -e 2888f65.0 AIKBV6smDMe5S/ne/usr/share/ca-certificates/mozilla/emSign_ECC_Root_CA_-_G3.crt /usr/bin/test a56daae944d3c60c/usr/sbin/iptables ication_Authorit--wait ache/go/1.24.11/-t test (dns block)
• periph.io
  • Triggering command: /update-job-proxy /update-job-proxy 4303997/b011/ (dns block)
  • Triggering command: /update-job-proxy /update-job-proxy -o br-d8f236fa6d57 -j DROP ertum_EC-384_CA.pem .8/x64/codeql/to/usr/share/ca-certificates/mozilla/Security_Communication_ECC_RootCA1.crt test eUeXgd7p LBT77L5xt rgo/bin/git test -e 2888f65.0 AIKBV6smDMe5S/ne/usr/share/ca-certificates/mozilla/emSign_ECC_Root_CA_-_G3.crt /usr/bin/test a56daae944d3c60c/usr/sbin/iptables ication_Authorit--wait ache/go/1.24.11/-t test (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)