Add GitHub PR template and issue templates

[haljac]

Problem

There are no PR or issue templates. Contributors must guess what information to include, leading to inconsistent issue reports and PRs that lack context, testing notes, or screenshots.

Scope of Work

1. PR template

Create .github/pull_request_template.md with sections:

• Summary — What does this PR do?
• Related issue — Closes #___
• Type of change — Bug fix / Feature / Refactor / Docs
• Checklist — Ran lint, ran format, tested locally, updated docs if needed

2. Issue templates (YAML forms)

Create .github/ISSUE_TEMPLATE/:

bug_report.yml

• Title prefix: [Bug]
• Fields: description, steps to reproduce, expected behavior, actual behavior, environment (browser/OS), screenshots

feature_request.yml

• Title prefix: [Feature]
• Fields: problem statement, proposed solution, alternatives considered, additional context

config.yml (optional)

• Add a blank issue option or link to Discussions

Acceptance Criteria

• .github/pull_request_template.md exists and renders correctly on new PRs
• .github/ISSUE_TEMPLATE/bug_report.yml creates a structured bug report form
• .github/ISSUE_TEMPLATE/feature_request.yml creates a structured feature request form
• Templates use YAML issue forms (not Markdown templates) for better UX
• All templates are tested by creating and discarding a draft issue/PR