Add GitHub issue and PR templates

[jeleel-muibi]

Summary

Adds GitHub issue forms for workload target defects, focused improvements, and usage or target clarification questions. Also adds a PR template so future changes have a consistent summary, validation, scope, and closure shape.

Closes #7

Validation

• Parsed all new issue template YAML files with PyYAML.
• Checked generated files for trailing whitespace and final newlines.

Scope

• This pull request is focused on one change.
• I have not included kubeconfigs, tokens, private domains, customer data, or secrets.
• I updated documentation, examples, or validation where the change needs them.
• I kept environment-specific wiring out of the public workload repo.