feat(ci): add OpenSSF Scorecard security scan workflow

[AnzalKhan16]

What

This pull request adds a dedicated GitHub Actions workflow to automatically run OpenSSF Scorecard security analysis for the repository.

The workflow generates a SARIF report, uploads it to GitHub Code Scanning, and stores the results as a workflow artifact for future reference.

Why

Fixes #237

Automating OpenSSF Scorecard scans improves repository security by continuously evaluating supply chain security best practices such as GitHub Actions security, workflow permissions, branch protection, dependency management, and repository configuration.

How

• Added a new .github/workflows/scorecard.yml workflow.
• Uses the official ossf/scorecard-action.
• Generates security analysis in SARIF format.
• Uploads SARIF results to GitHub Code Scanning.
• Uploads the generated report as a GitHub Actions artifact.
• Supports scheduled execution and manual workflow dispatch.

Testing

• go build ./... passes
• go test ./... passes
• go vet ./... passes
• golangci-lint run ./... passes
• N/A — workflow-only change (no application or eBPF code modified)

Checklist

• PR title follows Conventional Commits (feat(ci): ...)
• All commits are DCO-signed
• No unrelated changes pulled in
• Documentation updated where user-visible behavior changed
• Added/updated tests for new code paths
• No doctor rule changes