feat(ci): add GitHub Dependency Review workflow

[AnzalKhan16]

What

This pull request adds a GitHub Actions workflow that automatically reviews dependency changes introduced through pull requests using GitHub's official Dependency Review Action.

The workflow detects vulnerable dependency updates and provides an automated summary within pull requests.

Why

Fixes #240

Automating dependency review improves software supply chain security by identifying vulnerable or risky dependency changes before they are merged.

How

• Added a new .github/workflows/dependency-review.yml workflow.
• Uses GitHub's official Dependency Review Action.
• Runs on pull requests targeting the main branch.
• Fails the workflow if dependencies with High or Critical severity vulnerabilities are introduced.
• Posts a dependency review summary in the pull request.

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