Add structured bug and feature request forms #79

New reports currently start from an unstructured blank issue, so the details requested in CONTRIBUTING.md are easy to miss.

• Reproduce: open Frame's new-issue page and choose how to report a bug or request a feature.
• Expected: dedicated forms prompt for the information needed to understand each report.
• Actual: .github/ISSUE_TEMPLATE contains only config.yml; no bug or feature form is available.

The reporting guide asks for the operating system, relevant source-media details, reproduction steps, and FFmpeg logs for conversion behavior. A structured form can surface those prompts before an issue is submitted.

Actual screenshot

Upstream revision affa1fb contains only the issue-template configuration while CONTRIBUTING.md lists the reporting details:

Proposed scope

• Add a bug form for environment, media, reproduction, expected and actual behavior, logs, and supporting context.
• Add a feature form that starts with the problem, desired outcome, workflow context, and alternatives.
• Preserve blank issues for reports that do not fit either form.