ubuntu 24.04+ apparmor chromium, nix 24.11 golangci-lint

[rraymondgh]

Fix up chromium sandboxing errors in GitHub actions

• chromium apparmor. Creating an additional apparmor profile does work on dev server (25.10). However I could not find a way to apply to an action runner (using nekton/act)
• I tried using disable apparmor. This does not work with nektos/act
• hence used approach of disabling sandboxing in karma

gonlangci-lint

• have used an overlay in flake. nixos golangci-lint with a small adaptation
• opted for overlay rather that changing channel to 25.04 so that no other packages are updated and need to re-generate code (notably protoc) and hence increasing size of this PR