Configure Renovate for Go transitive dependencies with 3-day merge delay

[Copilot]

Enable Renovate to manage indirect (transitive) Go dependencies and run go mod tidy after updates, following the pattern from Breee/kubeswitch.

• Enable indirect Go deps: Renovate skips indirect dependencies by default; added a packageRules entry to explicitly enable them
• Add gomodTidy post-update: Keeps go.sum consistent after dependency bumps
• 3-day stabilization: Already configured via existing minimumReleaseAge: "3 days"

{
  "postUpdateOptions": ["gomodTidy"],
  "packageRules": [
    {
      "matchManagers": ["gomod"],
      "matchDepTypes": ["indirect"],
      "enabled": true
    }
  ]
}