Add Helm chart scaffold for Kubernetes deployments

[Copilot]

Adds a new devopsos scaffold helm command to generate production-ready Helm v3 charts. Users can now bootstrap Kubernetes deployments with templated Chart.yaml, values.yaml, and a complete set of Kubernetes manifests.

Changes

Core Implementation

• New scaffold_helm.py module generating chart structure with deployment, service, configmap templates, and helpers
• Validates chart names (lowercase alphanumeric + hyphens) and generates proper Helm v3 syntax
• Supports optional metadata (author, email, repository URL) with conditional inclusion in Chart.yaml

CLI Integration

• Added scaffold_helm_cmd() to devopsos.py with Typer decorators
• Options for chart metadata (name, version, description, app version) and app config (image, replicas, port, namespace)
• Environment variable support via DEVOPS_OS_HELM_* prefix

Testing & Quality

• 6 new test cases validating chart generation, template syntax, and CLI integration
• All 70 tests pass; CodeQL scan reports 0 alerts
• Follows existing scaffold patterns; parse_arguments accepts optional argv for testability

Example Usage

# Minimal: generates chart with sensible defaults
devopsos scaffold helm --name my-app

# Full: with metadata
devopsos scaffold helm --name my-app \
  --author "DevOps Team" \
  --author-email "devops@example.com" \
  --repo-url "https://github.com/example/my-app" \
  --replicas 3 \
  --image "ghcr.io/example/my-app:v1.0"

# Output structure:
# chart/
#   Chart.yaml
#   values.yaml
#   README.md
#   .helmignore
#   templates/
#     deployment.yaml
#     service.yaml
#     configmap.yaml
#     _helpers.tpl
#     NOTES.txt

Generated charts are immediately usable: helm install my-app ./chart

• Fixes [Feature]: Add Helm Deployment Template #33

[chefgs]

Looks good!