Add GitHub issue templates

[forthfate]

Goal

Add clear GitHub issue templates that help contributors report bugs and propose features.

Suggested scope

• Add a bug-report template.
• Add a feature-request template.
• Ask for reproduction steps, expected behavior, actual behavior, and relevant environment details.
• Keep the templates concise and welcoming for first-time contributors.

Acceptance criteria

• New issues can be opened through the available templates.
• Each template renders correctly on GitHub.
• The wording is written in clear English.