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
Medium risk because it introduces an automated workflow with contents/pull-requests write permissions that can open PRs and modify dependencies on a schedule.

Overview
Adds a new GitHub Actions workflow, vuln-remediation.yml, that runs weekly (and via manual dispatch) and calls the reusable kernel/security-workflows vulnerability remediation pipeline, inheriting secrets and using go.mod to select the Go version.

Introduces a minimal socket.yml (version: 2) configuration file.

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