feat(ci): add automated SBOM generation workflow

[AnzalKhan16]

What

This pull request adds a dedicated GitHub Actions workflow (sbom.yml) to automatically generate a Software Bill of Materials (SBOM) using Syft and upload it as a workflow artifact.

Why

Fixes #235

Generating an SBOM improves software supply chain transparency and provides a standardized inventory of project dependencies, aligning the project with modern DevSecOps best practices.

How

• Added a new sbom.yml workflow.
• Checks out the repository.
• Installs Syft.
• Generates an SPDX-formatted SBOM.
• Uploads the generated SBOM as a GitHub Actions artifact.

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