ci: add centralized vuln remediation workflow

[ulziibay-kernel]

Thin caller to the reusable 3-stage pipeline (triage → fix → PR) in kernel/infra. Per-repo config in .github/vuln-remediation.json.

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Note

Medium Risk
Introduces automation with contents and pull-requests write permissions that can create/modify branches and PRs. Risk is mainly around workflow trust and execution from the referenced reusable workflow.

Overview
Adds a new GitHub Actions workflow, vuln-remediation.yml, that runs on a weekly cron and via manual dispatch to call the reusable kernel/security-workflows vulnerability remediation pipeline (configured to use go.mod for Go version).

Adds a minimal socket.yml (version: 2) to enable Socket’s configuration/versioning.

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